[libc] [llvm] [libc] Refactor llogbl to be header-only and constexpr (PR #175376)

[Mathew Joseph via llvm-commits]

mathew1046 wrote:

@bassiounix I am really sorry about deleting that file. i misunderstood your message. about moving the function to designated section in main, do you perhaps meant to move the test to AllDouble section?

https://github.com/llvm/llvm-project/pull/175376