[mbedtls] How to rebuild the mbedTLS libraries about ot-nrf528xx HOT 3 CLOSED

1. Checkout nrf to https://github.com/MarekPorwisz/fw-nrfconnect-nrf/tree/vanilla_ot_nrf_security
2. Call west update
3. Checkout nrfxlib to https://github.com/MarekPorwisz/sdk-nrfxlib/tree/vanilla_ot_nrf_security (always after west update)
4. In case of using python3.6 => sudo apt-get install libpython3.6-dev
5. python3.6 -m pip install numpy west pyelftools
6. cd nrf/samples/openthread/cli
7. ./build_libs.sh
8. Built nrf_security is in openthread_mbedtls_out

**Notes:**
Keep in mind there are files not related to nrf_security in openthread that are placed in the nrf_security directory - do not remove them accidentally.
Oberon backend can be replaced with vanilla backend in the vanilla_nrf_sec.conf file if needed.

**Hint:**
When debugging FW build with the libraries (e.g. bare OpenThread) the debugger will not list the code as the source file paths will not match.
In such case one can check out the nrf_security branch used to build the libraries with git and then perform the path substitution in gdb.
Assuming that there are still libraries build by Marek in /home/map5/repo/ncs the command is as follows:
set substitute-path '/home/map5/repo/ncs' '<your_ncs_path>'