[llvm] [SafeStack] Add 'unsafealloc' metadata to identify unsafe AllocaInsts (PR #78941)

[Nikita Popov via llvm-commits]

nikic wrote:

Oh, I think I'm confusing the StackSafety analysis with the SafeStack feature. I thought this was related to the recent enablement of StackSafety in asan.

Well, at least the point about LangRef still stands...

https://github.com/llvm/llvm-project/pull/78941