[clang] [llvm] [LLVM][Clang][AArch64] Implement AArch64 build attributes (PR #118771)

[via llvm-commits]

sivan-shani wrote:

@nico @antmox the very same 5 .ll tests passed upstream pre-merge
https://buildkite.com/llvm-project/github-pull-requests/builds/139398#01948e1c-bd4f-41d6-878b-789113e2cbea
Not sure how to understand the later failure. 
Still investigating.

https://github.com/llvm/llvm-project/pull/118771