[clang] [clang] Allow relational comparisons between unequal pointers to `void` in constant expressions (PR #89449)

[Vlad Serebrennikov via cfe-commits]

https://github.com/Endilll commented:

Changes to DR tests look good to me, thank you!
Can you send an email to Jens Maurer asking him to mark 2526 as superseded by 2749?
I'm also somewhat suspicious of the fact that we check only LHS for being `void*`, but that's what we did previously as well, so this might be fine.

https://github.com/llvm/llvm-project/pull/89449