android-21 sysroot include stdatomic.h which seems to be wrong
Both gcc and clang already have own stdatomic.h, so having additional one in sysroot looks wrong. Also, it seems that stdatomic.h included in android-21 sysroot, is broken - it cause compiler errors when building third-party open source projects (python-3.5, for example). If we remove stdatomic.h from sysroot, compiler error is gone. This need to be investigated and properly fixed - either providing proper stdatomic.h in sysroot for all API levels, or removing it from sysroot and use one provided by compiler.