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

[Mital Ashok via cfe-commits]

MitalAshok wrote:

> Will that include fixing clang incorrectly warning when an inheritance model is explicitly specified?

Yes, I have a WIP of it here #98010 where that doesn't get a warning (https://github.com/llvm/llvm-project/pull/98010/files#diff-bec1ae40e5793adbd61e7a9dc41a4715a06e27888a384c0752bb6b4b09a1075fR20-R21)

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