[clang] [Clang][HTO] Add clang attribute for propagating llvm-level information (PR #83059)

[William Moses via cfe-commits]

wsmoses wrote:

Okay, the AnnotateAttr doesn't create LLVM string attributes, it creates LLVM metadata, but that should sufice, closing.

https://github.com/llvm/llvm-project/pull/83059