[clang] [Clang][Sema] Disallow applying `onwership_returns` to functions that return non-pointers (PR #99564)

[via cfe-commits]

https://github.com/Sirraide commented:

The implementation in and of itself lgtm, except for two minor comments.

That said, I have never heard of this attribute before, and our documentation seems to be rather lacking in this respect. Maybe @AaronBallman has an idea as to who might know more about this...

https://github.com/llvm/llvm-project/pull/99564