[clang] Allow ObjC writeback conversion in cleanup attribute type check (PR #195318)

[John McCall via cfe-commits]

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

LGTM. I wonder if there's some common "does this works as a parameter initialization routine we could use".

Could you make sure there's an ObjC++ test?

https://github.com/llvm/llvm-project/pull/195318