[llvm] Add Apple M4 host detection (PR #117530)

[Mads Marquart via llvm-commits]

madsmtm wrote:

CC @jroelofs who reviewed https://github.com/llvm/llvm-project/pull/82100 (I don't know the procedures for who to ask, sorry if you're the wrong person to tag).

https://github.com/llvm/llvm-project/pull/117530