[libc] [llvm] [libc] Add more functions in CPP/bit.h (PR #73814)

[via llvm-commits]

https://github.com/michaelrj-google commented:

The implementations LGTM, but do you have plans to use all of these functions?  If they don't have a use case right now they seem like they'd be easy enough to add later.

https://github.com/llvm/llvm-project/pull/73814