[libcxx-commits] [libcxx] [libc++] Improve performance of std::atomic_flag on Windows (PR #163524)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 approved this pull request.

I'm happy with the changes, but let's wait for others to comment.

https://github.com/llvm/llvm-project/pull/163524