[clang] [clang][AST] fix dereference on class/struct layouts check. (PR #83686)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik requested changes to this pull request.

We need a minimal reproducer here. Looking at the bug report it is not clear to me if this is the correct fix or not. After we have a reproducer we would need a test added to the PR and a release note.

https://github.com/llvm/llvm-project/pull/83686