Revert "Encapsulate PassManager debug flags to avoid static init and cxa_exit."

Working on a better solution to this.

This reverts commit 7d4e9934e7ca83094c5cf41346966c8350179ff2.
asan/tsan/msan: use builtin atomic operations when available
this should fix episodic crashes on ARM/PPC
x86_32 is still broken