[clang] [cfi][CodeGen] Call SetLLVMFunctionAttributes{, ForDefinition} on __cf… (PR #78253)

[Pavel Kosov via cfe-commits]

kpdev wrote:

> Should we add a release note to `clang/docs/ReleaseNotes.rst` so users know about the changes?

Seems reasonable ) Should I add it somewhere to [`Sanitizers`](https://github.com/llvm/llvm-project/blob/main/clang/docs/ReleaseNotes.rst#sanitizers) ? 

https://github.com/llvm/llvm-project/pull/78253