[clang] [clang] Fix the crash when dumping deserialized decls (PR #133395)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

> I'm happy to split the patch. I agree that (2) requires more thought and careful consideration. I'm not sure I'll have time to finish it before my leave, so I might have to leave it to you. But I can take care of (1).

Yeah, I feel it makes sense to abandon this until you are back or we really need it. Forwarding the callbacks is a clear improvement anyway.

https://github.com/llvm/llvm-project/pull/133395