[libc-commits] [libc] [libc] Replace `MutexLock` with `cpp::lock_guard` (PR #89340)

[Guillaume Chatelet via libc-commits]

https://github.com/gchatelet commented:

Just a little nit, otherwise LGTM.
Can you land this PR or do you need me to land it?

https://github.com/llvm/llvm-project/pull/89340