Hi,
I'm the archlinux maintainer of your fork. Building the actual branch fails with the following error:

  CC       synaptics.lo
  CC       synproto.lo
In file included from /usr/include/string.h:634:0,
                 from /usr/include/xorg/os.h:53,
                 from /usr/include/xorg/misc.h:115,
                 from /usr/include/xorg/xf86str.h:37,
                 from /usr/include/xorg/xf86Xinput.h:54,
                 from synproto.h:36,
                 from synproto.c:24:
/usr/include/xorg/os.h:579:1: error: expected identifier or '(' before '__extension__'
 strndup(const char *str, size_t n);
 ^
Makefile:504: recipe for target 'synproto.lo' failed
make[2]: *** [synproto.lo] Error 1
make[2]: Leaving directory '/home/diego/xps13/PKGs/xf86-input-synaptics-xswipe-git/src/xf86-input-synaptics-xswipe-git/src'
Makefile:499: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/home/diego/xps13/PKGs/xf86-input-synaptics-xswipe-git/src/xf86u p-input-synaptics-xswipe-git'
Makefile:407: recipe for target 'all' failed
make: *** [all] Error 2

The culprit is the new glibc version and the upstream fix is here.

make[2]: Entering directory '/home/jb/Projects/xserver-xorg-input-synaptics/src'
  CC       synproto.lo
In file included from /usr/include/string.h:634:0,
                 from /usr/include/xorg/os.h:53,
                 from /usr/include/xorg/misc.h:115,
                 from /usr/include/xorg/xf86str.h:37,
                 from /usr/include/xorg/xf86.h:44,
                 from /usr/include/xorg/xf86Xinput.h:54,
                 from synproto.h:36,
                 from synproto.c:24:
/usr/include/xorg/os.h:541:1: error: expected identifier or '(' before '__extension__'
 strndup(const char *str, size_t n);
 ^
Makefile:504: recipe for target 'synproto.lo' failed
make[2]: *** [synproto.lo] Error 1
make[2]: Leaving directory '/home/jb/Projects/xserver-xorg-input-synaptics/src'

Looks like os.h duplicates prototypes for some system functions unless xorg-server.h is included first, according to this discussion http://lists.x.org/archives/xorg-devel/2014-July/043067.html

Currently os.h cannot be included safely (without it creating duplicate
prototypes for system functions) without first including one of:
dix-config.h
xorg-server.h
xorg-config.h

When ./autogen.sh be executed with gcc 5.2.1-22ubuntu2 on Ubuntu 15.10, the script exit with compile error.

The full text of config.log is below:

This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.

It was created by xf86-input-synaptics configure 1.7.99, which was
generated by GNU Autoconf 2.69. Invocation command line was

$ ./configure

---------

Platform.

---------

hostname = shuduo-ThinkPad-E450
uname -m = x86_64
uname -r = 4.2.0-27-generic
uname -s = Linux
uname -v = #32-Ubuntu SMP Fri Jan 22 04:49:08 UTC 2016

/usr/bin/uname -p = unknown
/bin/uname -X = unknown

/bin/arch = unknown
/usr/bin/arch -k = unknown
/usr/convex/getsysinfo = unknown
/usr/bin/hostinfo = unknown
/bin/machine = unknown
/usr/bin/oslevel = unknown
/bin/universe = unknown

PATH: /home/shuduo/bin
PATH: /home/shuduo/bin
PATH: /usr/local/sbin
PATH: /usr/local/bin
PATH: /usr/sbin
PATH: /usr/bin
PATH: /sbin
PATH: /bin
PATH: /usr/games
PATH: /usr/local/games
PATH: /home/shuduo/work/android/android-studio/bin
PATH: /home/shuduo/tools/go/bin

-----------

Core tests.

-----------

configure:2316: checking for a BSD-compatible install
configure:2384: result: /usr/bin/install -c
configure:2395: checking whether build environment is sane
configure:2450: result: yes
configure:2601: checking for a thread-safe mkdir -p
configure:2640: result: /bin/mkdir -p
configure:2647: checking for gawk
configure:2663: found /usr/bin/gawk
configure:2674: result: gawk
configure:2685: checking whether make sets $(MAKE)
configure:2707: result: yes
configure:2736: checking whether make supports nested variables
configure:2753: result: yes
configure:2941: checking build system type
configure:2955: result: x86_64-unknown-linux-gnu
configure:2975: checking host system type
configure:2988: result: x86_64-unknown-linux-gnu
configure:3029: checking how to print strings
configure:3056: result: printf
configure:3089: checking for style of include used by make
configure:3117: result: GNU
configure:3188: checking for gcc
configure:3204: found /home/shuduo/bin/gcc
configure:3215: result: gcc
configure:3444: checking for C compiler version
configure:3453: gcc --version >&5
gcc (Ubuntu 5.2.1-22ubuntu2) 5.2.1 20151010
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

configure:3464: $? = 0
configure:3453: gcc -v >&5
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.2.1-22ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2)
configure:3464: $? = 0
configure:3453: gcc -V >&5
gcc: error: unrecognized command line option '-V'
gcc: fatal error: no input files
compilation terminated.
configure:3464: $? = 1
configure:3453: gcc -qversion >&5
gcc: error: unrecognized command line option '-qversion'
gcc: fatal error: no input files
compilation terminated.
configure:3464: $? = 1
configure:3484: checking whether the C compiler works
configure:3506: gcc conftest.c >&5
configure:3510: $? = 0
configure:3558: result: yes
configure:3561: checking for C compiler default output file name
configure:3563: result: a.out
configure:3569: checking for suffix of executables
configure:3576: gcc -o conftest conftest.c >&5
configure:3580: $? = 0
configure:3602: result:
configure:3624: checking whether we are cross compiling
configure:3632: gcc -o conftest conftest.c >&5
configure:3636: $? = 0
configure:3643: ./conftest
configure:3647: $? = 0
configure:3662: result: no
configure:3667: checking for suffix of object files
configure:3689: gcc -c conftest.c >&5
ccache: error: Failed to create directory /opt/ccache/tmp: Permission denied
configure:3693: $? = 1
configure: failed program was:
| /* confdefs.h /
| #define PACKAGE_NAME "xf86-input-synaptics"
| #define PACKAGE_TARNAME "xf86-input-synaptics"
| #define PACKAGE_VERSION "1.7.99"
| #define PACKAGE_STRING "xf86-input-synaptics 1.7.99"
| #define PACKAGE_BUGREPORT "https://bugs.freedesktop.org/enter_bug.cgi?product=xorg"
| #define PACKAGE_URL ""
| #define PACKAGE "xf86-input-synaptics"
| #define VERSION "1.7.99"
| / end confdefs.h. */
|
| int
| main ()
| {
|
| ;
| return 0;
| }
configure:3707: error: in /home/shuduo/work/misc/xserver-xorg-input-synaptics': configure:3709: error: cannot compute suffix of object files: cannot compile Seeconfig.log' for more details

----------------

Cache variables.

----------------

ac_cv_build=x86_64-unknown-linux-gnu
ac_cv_env_CC_set=
ac_cv_env_CC_value=
ac_cv_env_CFLAGS_set=
ac_cv_env_CFLAGS_value=
ac_cv_env_CPPFLAGS_set=
ac_cv_env_CPPFLAGS_value=
ac_cv_env_CPP_set=
ac_cv_env_CPP_value=
ac_cv_env_LDFLAGS_set=
ac_cv_env_LDFLAGS_value=
ac_cv_env_LIBEVDEV_CFLAGS_set=
ac_cv_env_LIBEVDEV_CFLAGS_value=
ac_cv_env_LIBEVDEV_LIBS_set=
ac_cv_env_LIBEVDEV_LIBS_value=
ac_cv_env_LIBS_set=
ac_cv_env_LIBS_value=
ac_cv_env_MTDEV_CFLAGS_set=
ac_cv_env_MTDEV_CFLAGS_value=
ac_cv_env_MTDEV_LIBS_set=
ac_cv_env_MTDEV_LIBS_value=
ac_cv_env_PKG_CONFIG_LIBDIR_set=
ac_cv_env_PKG_CONFIG_LIBDIR_value=
ac_cv_env_PKG_CONFIG_PATH_set=
ac_cv_env_PKG_CONFIG_PATH_value=
ac_cv_env_PKG_CONFIG_set=
ac_cv_env_PKG_CONFIG_value=
ac_cv_env_XI_CFLAGS_set=
ac_cv_env_XI_CFLAGS_value=
ac_cv_env_XI_LIBS_set=
ac_cv_env_XI_LIBS_value=
ac_cv_env_XORG_CFLAGS_set=
ac_cv_env_XORG_CFLAGS_value=
ac_cv_env_XORG_LIBS_set=
ac_cv_env_XORG_LIBS_value=
ac_cv_env_XORG_MALLOC_DEBUG_ENV_set=
ac_cv_env_XORG_MALLOC_DEBUG_ENV_value=
ac_cv_env_XTST_CFLAGS_set=
ac_cv_env_XTST_CFLAGS_value=
ac_cv_env_XTST_LIBS_set=
ac_cv_env_XTST_LIBS_value=
ac_cv_env_build_alias_set=
ac_cv_env_build_alias_value=
ac_cv_env_host_alias_set=
ac_cv_env_host_alias_value=
ac_cv_env_target_alias_set=
ac_cv_env_target_alias_value=
ac_cv_host=x86_64-unknown-linux-gnu
ac_cv_path_install='/usr/bin/install -c'
ac_cv_path_mkdir=/bin/mkdir
ac_cv_prog_AWK=gawk
ac_cv_prog_ac_ct_CC=gcc
ac_cv_prog_make_make_set=yes
am_cv_make_support_nested_variables=yes

-----------------

Output variables.

-----------------

ACLOCAL='${SHELL} /home/shuduo/work/misc/xserver-xorg-input-synaptics/missing aclocal-1.15'
ADMIN_MAN_DIR=''
ADMIN_MAN_SUFFIX=''
AMDEPBACKSLASH=''
AMDEP_FALSE='#'
AMDEP_TRUE=''
AMTAR='$${TAR-tar}'
AM_BACKSLASH=''
AM_DEFAULT_V='$(AM_DEFAULT_VERBOSITY)'
AM_DEFAULT_VERBOSITY='1'
AM_V='$(V)'
APP_MAN_DIR=''
APP_MAN_SUFFIX=''
AR=''
AUTOCONF='${SHELL} /home/shuduo/work/misc/xserver-xorg-input-synaptics/missing autoconf'
AUTOHEADER='${SHELL} /home/shuduo/work/misc/xserver-xorg-input-synaptics/missing autoheader'
AUTOMAKE='${SHELL} /home/shuduo/work/misc/xserver-xorg-input-synaptics/missing automake-1.15'
AWK='gawk'
BASE_CFLAGS=''
BUILD_EVENTCOMM_FALSE=''
BUILD_EVENTCOMM_TRUE=''
BUILD_PS2COMM_FALSE=''
BUILD_PS2COMM_TRUE=''
BUILD_PSMCOMM_FALSE=''
BUILD_PSMCOMM_TRUE=''
CC='gcc'
CCDEPMODE=''
CFLAGS=''
CHANGELOG_CMD=''
CPP=''
CPPFLAGS=''
CWARNFLAGS=''
CYGPATH_W='echo'
DEBUG_FALSE=''
DEBUG_TRUE=''
DEFS=''
DEPDIR='.deps'
DLLTOOL=''
DRIVER_MAN_DIR=''
DRIVER_MAN_SUFFIX=''
DSYMUTIL=''
DUMPBIN=''
ECHO_C=''
ECHO_N='-n'
ECHO_T=''
EGREP=''
ENABLE_UNIT_TESTS_FALSE=''
ENABLE_UNIT_TESTS_TRUE=''
EXEEXT=''
FGREP=''
FILE_MAN_DIR=''
FILE_MAN_SUFFIX=''
GREP=''
HAS_XORG_CONF_DIR_FALSE=''
HAS_XORG_CONF_DIR_TRUE=''
INSTALL_CMD=''
INSTALL_DATA='${INSTALL} -m 644'
INSTALL_PROGRAM='${INSTALL}'
INSTALL_SCRIPT='${INSTALL}'
INSTALL_STRIP_PROGRAM='$(install_sh) -c -s'
LD=''
LDFLAGS=''
LIBEVDEV_CFLAGS=''
LIBEVDEV_LIBS=''
LIBOBJS=''
LIBS=''
LIBTOOL=''
LIB_MAN_DIR=''
LIB_MAN_SUFFIX=''
LIPO=''
LN_S=''
LTLIBOBJS=''
MAKEINFO='${SHELL} /home/shuduo/work/misc/xserver-xorg-input-synaptics/missing makeinfo'
MANIFEST_TOOL=''
MAN_SUBSTS=''
MISC_MAN_DIR=''
MISC_MAN_SUFFIX=''
MKDIR_P='/bin/mkdir -p'
MTDEV_CFLAGS=''
MTDEV_LIBS=''
NM=''
NMEDIT=''
OBJDUMP=''
OBJEXT=''
OTOOL64=''
OTOOL=''
PACKAGE='xf86-input-synaptics'
PACKAGE_BUGREPORT='https://bugs.freedesktop.org/enter_bug.cgi?product=xorg'
PACKAGE_NAME='xf86-input-synaptics'
PACKAGE_STRING='xf86-input-synaptics 1.7.99'
PACKAGE_TARNAME='xf86-input-synaptics'
PACKAGE_URL=''
PACKAGE_VERSION='1.7.99'
PATH_SEPARATOR=':'
PKG_CONFIG=''
PKG_CONFIG_LIBDIR=''
PKG_CONFIG_PATH=''
RANLIB=''
SED=''
SET_MAKE=''
SHELL='/bin/bash'
STRICT_CFLAGS=''
STRIP=''
VERSION='1.7.99'
XI_CFLAGS=''
XI_LIBS=''
XORG_CFLAGS=''
XORG_LIBS=''
XORG_MALLOC_DEBUG_ENV=''
XORG_MAN_PAGE=''
XTST_CFLAGS=''
XTST_LIBS=''
ac_ct_AR=''
ac_ct_CC='gcc'
ac_ct_DUMPBIN=''
am__EXEEXT_FALSE=''
am__EXEEXT_TRUE=''
am__fastdepCC_FALSE=''
am__fastdepCC_TRUE=''
am__include='include'
am__isrc=''
am__leading_dot='.'
am__nodep='_no'
am__quote=''
am__tar='$${TAR-tar} chof - "$$tardir"'
am__untar='$${TAR-tar} xf -'
bindir='${exec_prefix}/bin'
build='x86_64-unknown-linux-gnu'
build_alias=''
build_cpu='x86_64'
build_os='linux-gnu'
build_vendor='unknown'
configdir=''
datadir='${datarootdir}'
datarootdir='${prefix}/share'
docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
dvidir='${docdir}'
exec_prefix='NONE'
host='x86_64-unknown-linux-gnu'
host_alias=''
host_cpu='x86_64'
host_os='linux-gnu'
host_vendor='unknown'
htmldir='${docdir}'
includedir='${prefix}/include'
infodir='${datarootdir}/info'
inputdir=''
install_sh='${SHELL} /home/shuduo/work/misc/xserver-xorg-input-synaptics/install-sh'
libdir='${exec_prefix}/lib'
libexecdir='${exec_prefix}/libexec'
localedir='${datarootdir}/locale'
localstatedir='${prefix}/var'
mandir='${datarootdir}/man'
mkdir_p='$(MKDIR_P)'
oldincludedir='/usr/include'
pdfdir='${docdir}'
prefix='NONE'
program_transform_name='s,x,x,'
psdir='${docdir}'
sbindir='${exec_prefix}/sbin'
sdkdir=''
sharedstatedir='${prefix}/com'
sysconfdir='${prefix}/etc'
target_alias=''

-----------

confdefs.h.

-----------

/* confdefs.h */

define PACKAGE_NAME "xf86-input-synaptics"

define PACKAGE_TARNAME "xf86-input-synaptics"

define PACKAGE_VERSION "1.7.99"

define PACKAGE_STRING "xf86-input-synaptics 1.7.99"

define PACKAGE_BUGREPORT "https://bugs.freedesktop.org/enter_bug.cgi?product=xorg"

define PACKAGE_URL ""

define PACKAGE "xf86-input-synaptics"

define VERSION "1.7.99"

configure: exit 1

make all-recursive
make[1]: Entering directory '/home/aly/zzz/xserver-xorg-input-synaptics'
Making all in include
make[2]: Entering directory '/home/aly/zzz/xserver-xorg-input-synaptics/include'
make[2]: Nothing to be done for 'all'.
make[2]: Leaving directory '/home/aly/zzz/xserver-xorg-input-synaptics/include'
Making all in src
make[2]: Entering directory '/home/aly/zzz/xserver-xorg-input-synaptics/src'
CC synproto.lo
In file included from /usr/include/string.h:630:0,
from /usr/include/xorg/os.h:53,
from /usr/include/xorg/misc.h:116,
from /usr/include/xorg/xf86str.h:37,
from /usr/include/xorg/xf86.h:44,
from /usr/include/xorg/xf86Xinput.h:54,
from synproto.h:36,
from synproto.c:24:
/usr/include/xorg/os.h:590:1: error: expected identifier or ‘(’ before ‘extension’
strndup(const char str, size_t n);
^
Makefile:515: recipe for target 'synproto.lo' failed
make[2]: ** [synproto.lo] Error 1
make[2]: Leaving directory '/home/aly/zzz/xserver-xorg-input-synaptics/src'
Makefile:511: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/home/aly/zzz/xserver-xorg-input-synaptics'
Makefile:420: recipe for target 'all' failed
make: *** [all] Error 2