This reverts commit 25073a4ecf.
This breaks non-x86 OpenMP builds for a while now. Until a solution is
ready to be upstreamed we revert the feature and unblock those builds.
See:
https://reviews.llvm.org/rG25073a4ecfc9b2e3cb76776185e63bfdb094cd98#1005821
and
https://reviews.llvm.org/rG25073a4ecfc9b2e3cb76776185e63bfdb094cd98#1005821
The currently proposed fix (D104788) seems not to be ready yet:
https://reviews.llvm.org/D104788#2841928