[clang] [clang] Fix darwin-related tests' REQUIRES annotation (PR #130138)

[Steven Wu via cfe-commits]

https://github.com/cachemeifyoucan commented:

I think the fix makes sense for a linux toolchain running on Darwin. I am still surprised that you have a "system-darwin" platform where you don't want the default target triple to be darwin.

I am ok with the fix but it will be good to update the REQUIRES to cover MacOSX target as well. 



https://github.com/llvm/llvm-project/pull/130138