[llvm-branch-commits] [llvm] [clang] [clang] Function Multi Versioning supports IFunc lowerings on Darwin platforms (PR #73688)

[Fangrui Song via llvm-branch-commits]

https://github.com/MaskRay approved this pull request.

This PR just updates `supportsIFunc` and extends clang tests. LGTM

https://github.com/llvm/llvm-project/pull/73688