Android O IOT Preview 6 (4475743)
Switch to bionic stdatomic.h.

We need to use bionic's stdatomic.h in order to have proper C11/C++11
behavior.

Bug: http://b/62580008
Test: https://goto.google.com/clang-4393122-testing
Change-Id: I392cc660d72fe31da6b516706b377e651a14ca82
1 file changed