[libc-commits] [libc] [libc] Implement sigwait (PR #237572)

[Alexey Samsonov via libc-commits]

https://github.com/vonosmas requested changes to this pull request.

I will leave a couple of comments, but let's wait for the other PR before proceeding with this one. Also, I've allowed the workflows to run - please act on their results when they're done.

https://github.com/llvm/llvm-project/pull/237572