[libc] [clang] [llvm] [Libc] Give more functions restrict qualifiers (PR #78061)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> > LLVM changes look unrelated, it was originally copied from OpenBSD it seems. But it's not a major issue.
> 
> FWIW I opened a few PRs in FreeBSD regarding this.

Yeah, go ahead and move that portion there so the people who know more about LLVM's regex can look at it compared to the `libc` team.

https://github.com/llvm/llvm-project/pull/78061