[libc-commits] [libc] [libc] make clock_conversion.h common and document it (PR #167723)

[Shreeyash Pandey via libc-commits]

bojle wrote:

Hi @SchrodingerZhu @michaelrj-google, could use your review on this. Up in the stack are PRs https://github.com/llvm/llvm-project/pull/167719/ and https://github.com/llvm/llvm-project/pull/167722. They should pass build checks once this is merged.

https://github.com/llvm/llvm-project/pull/167723