[compiler-rt] [Darwin][CompilerRT] Set compiler ID to 'Clang' for Compiler RT Tests for Apple Clang (PR #121858)

[Alexander Richardson via llvm-commits]

https://github.com/arichardson requested changes to this pull request.

Would be nice if this could be done in the test suite instead. I think this is broken though as it stands now.

https://github.com/llvm/llvm-project/pull/121858