[clang] [clang] Fix constant evaluation of member pointer access into sibling class. (PR #150829)

[Erich Keane via cfe-commits]

erichkeane wrote:

I think you're good to go, feel free to click the merge button.  Let me know if you don't have commit rights yet, and I'll click it for you :) 

https://github.com/llvm/llvm-project/pull/150829