This is needed to make L work correctly, and bionic tests pass
again, after applying the equivalent of
commit 00aaea3645 there.
It makes the preexisting code that uses __sync implementations
much more useful, although we should no longer be exercising that
code in AOSP.
Specifically fixes:
We were invoking __has_extension and __has_builtin for GCC compilations.
They're clang specific. Restructured the tests.
The __sync implementation was not defining the LOCK_FREE macros.
ATOMIC_VAR_INIT was using named field initializations. These are a
C, not C++, feature, that is not supported by g++ 4.6.
The stdatomic bionic test still failed with 4.6 and glibc with our
questionable LOCK_FREE macro implementation. Don't run that piece
with 4.6.
In L, this is a prerequisite for fixing:
Bug:16880454
Bug:16513433
Change-Id: I9b61e42307f96a114dce7552b6ead4ad1c544eab
32429606bf