[clang] [Clang][CodeGen] Fix `CanSkipVTablePointerInitialization` for dynamic classes with a trivial anonymous union (PR #84651)

[Max Winkler via cfe-commits]

MaxEW707 wrote:

@AaronBallman @efriedma-quic 

Pinging you two for a review. Looking through the history of `CGClass.cpp` you guys appear to be the common reviewers and the CodeOwners file didn't have any information for who owns `CodeGen`.

Feel free to add anyone who may be a better fit. Thanks :).

https://github.com/llvm/llvm-project/pull/84651