[clang] [Clang] Fix Microsoft ABI inheritance model when member pointer is used in a base specifier (PR #91990)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

This generally LGTM but I'd love to hear from @rnk or @zmodem as they are quite knowledgeable about the MS ABI in general.

https://github.com/llvm/llvm-project/pull/91990