[clang] [ObjC] Check entire chain of superclasses to see if class layout is statically known (PR #81335)

[Youngsuk Kim via cfe-commits]

JOE1994 wrote:

> @JOE1994 Thoughts on this?

I'm not an ideal reviewer for this as I'm unfamiliar with ObjC side of Clang,
but I'll come back to leave a review and to help merge this if this doesn't get merged by the end of the day :)

https://github.com/llvm/llvm-project/pull/81335