[compiler-rt] [ASan][Windows] Synchronizing ASAN init on Windows (PR #71833)

[Zack Johnson via llvm-commits]

zacklj89 wrote:

Apologies @vitalybuka, just updated it.

The comment on the other PR about moving to `asan_win.cpp` seems ok, but I think that having all thread related code in `asan_thread.cpp` is fine too.

I will be out of office until the new year, so if this doesn't get merged I'll check back in then. Happy holidays!

https://github.com/llvm/llvm-project/pull/71833