[clang] [Darwin][Driver][clang] arm64-apple-none-macho is missing the Apple macros from arm-apple-none-macho (PR #122427)

[Ian Anderson via cfe-commits]

ian-twilightcoder wrote:

> LLVM Buildbot has detected a new failure on builder `openmp-offload-libc-amdgpu-runtime` running on `omp-vega20-1` while building `clang` at step 7 "Add check check-offload".
> 
> Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/11512
> 
> Here is the relevant piece of the build log for the reference

It doesn't _look_ like the failure is actually related to this change. Possibly a flaky test?

https://github.com/llvm/llvm-project/pull/122427