Use @llvm.threadlocal.address intrinsic to access TLS variable

This is successor for D125291. This revision would try to use
@llvm.threadlocal.address in clang to access TLS variable. The reason
why the OpenMP tests contains a lot of change is that they uses
utils/update_cc_test_checks.py to update their tests.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D129833