suggest: improve path management in gui/about_dialog/about_dialog.cc about mozc HOT 1 CLOSED

Starting with r61, we have "product_icon_32bpp-128.png" at the following 
location.
http://code.google.com/p/mozc/source/browse/trunk/src/data/images/product_icon_3
2bpp-128.png

This file will be embedded into the mozc_tool and finally pointed from the 
about dialog by 'new QImage(":/product_logo.png")' as you found.
See
http://code.google.com/p/mozc/source/browse/trunk/src/gui/about_dialog/about_dia
log.qrc
about how this works.

If you want to use any different product logo, please replace
  src/data/images/product_icon_32bpp-128.png
before you start the build.

I hope this helps you.