thanks to Supreeth Herle for reporting.

clang have changed its default standard to C11 compilation and is stricter.
Ensure use of gnu89 standard to use pthread extension for --castxml-gccxml

It can't link because nas_config.c and rb_config.c was commented.

The unit simulators may still need some checks.

plus some cleanup here and there

The T only works when it's TRUE, the version without shared memory
is not supported anymore.

probably not be here.

Also modified CMakeLists.txt to run asn1tostruct.py at cmake time,
because the generated Makefile was wrong. When compiling with -j4
it would mess up by calling fix_asn1 twice with a weird timing,
leading to failures.

The strategy is rather basic. Files with warnings are replaced
by an edited copy that triggers no warning.

We take care to check that the replaced file is the same as the
one that was analyzed at the time of warning removal (through
checking its SHA1).

There is a new bash script "fix_asn1" in cmake_targets/tools
and the files replacing the existing ones are in
cmake_targets/tools/fix_asn1.data.

Make it compile on 15.10 (problem with gcc-xml not resolved, may be do as in openair-cn: disable it, it is only needed for ITTI ANALYZER)

update CMakelists.txt - update build_oai (add checks for args validity , minor update to linked libraries)

added avx2 optimized turbo decoder for 16-bit LLR.  This decoder parallelizes by decoding 2 code segments concurrently. requires updates dlsch_decoding.c to identify when new parallel version can be used. other minor changes related to memory allocations for future avx2 optimizations (32-byte alignment).