[llvm] [LLVM][Clang][AArch64] Implement AArch64 build attributes (PR #123990)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Useful practices:

* Relands and Fixes: If a change is a reland of a previous change, I will explicitly mention it (e.g., "Reland #118771"). I will also state what problems the change fixes.
* I would prioritize the order based on the consumer-producer relationship. In the specific example you provided (MC/binary utility, linker, codegen toggle), I will suggest changes in that order:
  + MC/binary utility. The description could mention how existing consumers will handle the new section.
  + Linker
  + Codegen toggle


https://github.com/llvm/llvm-project/pull/123990