Some toolchains (such as sysmobts 201705 one) containing the TLS bug on
old ARM gcc versions (<7.3.0) also crash if the initial workaround found
is aplied (CFLAGS="-mtls-dialect=gnu2"). In that scenario, let's provide
a way to disable the workaround (to avoid "ld" crashing) and warn the
user about requirement to build with -O0 to avoid runtime crashes.
Related: OS#4062
Related: SYS#4628
Change-Id: I04ff8c702eabcf4f6e7b59e11aece2744267cefe
Check if compiler being used contains the bug. GCC 7.3.0 is the oldest
version containing the fix, and version 6.3.0 is known to contain the
bug. Bug is only known to appear so far only on ARM32. If the bug is
present, gcc will generate a wrong binary which wil lend up segfaulting
when accessing TLS (__thread) variables under certain conditions.
Related: OS#4062
Related: SYS#4628
Change-Id: I8acc2cf41b73da0c3290f1cefd79f2bc68b0e77d