This is an alternate, somewhat simpler, fix that makes it safe to
include both <atomic> and <stdatomic.h> from C++ code in either order.
It means that C code consistently uses one implementation of atomics
and C++ another. We still have to make sure that those two
implementations interoperate correctly at runtime; in particular,
any flavor of atomic object needs to be represented exactly like the
underlying type, with the proper alignment constraint.
Bug:17007799
Change-Id: Iffcfc5220d8fa150f89dd083a121b24d23f268fc
(cherry picked from commit 019d3958118b7dc3ec8444ad2accca50c268b737)
Some platform code is apparently compiled with switches that do
not support char16_t and char32_t. This caused stdatomic.h to fail
to compile. This CL makes stdatomic.h usable in those environments.
(cherry picked from commit 8b002362d996859ebfc8588d6859a9a79203dc27)
Change-Id: Ie5a17f20b8b545c97128d00605b4eabd2a6bfe3e
