These headers used to be guarded only on PowerPC64 Linux or FreeBSD, but
they can also be enabled for AIX OS target since it's big-endian ready.
Reviewed By: shchenz
Differential Revision: https://reviews.llvm.org/D129461
These tests are dumped without optimization, which makes them too
lengthy and contain meaningless load/stores. Clean them up to prepare
for future headers update.
Qiu Chaofan