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

[Steven Wu via cfe-commits]

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

LGTM. Thanks for looking into the question I have. I slightly prefer if it is an option, making your platform either be darwin, or be entirely not darwin. But since you only need test update, I am ok with it since it doesn't make the things too complicated. 

Will be good if you can have a public bot for your configuration, otherwise future tests might not be aware of the existence of your special platform and break again.

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