[clang] [clang codegen] Emit !unpredictable metadata more consistently. (PR #111065)

[Erich Keane via cfe-commits]

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

Would this have value with a release note?  Perhaps mention what we can do 'better' because of it?

https://github.com/llvm/llvm-project/pull/111065