Roll back the use of C++11 atomics.

This was an incorrect use of std::atomic_thread_fence() because our
loads and stores do not involve atomic types as currently written.

Change-Id: I0bb6feb781ce52887603367d299df9b3844179e2
Reviewed-on: https://code-review.googlesource.com/3711
Reviewed-by: Paul Wankadia <junyer@google.com>
1 file changed