[clang] [Clang] [Sema] Handle placeholders in '.*' expressions (PR #83103)

[Andrew Kaster via cfe-commits]

ADKaster wrote:

@AaronBallman @Sirraide would this patch be reasonable to backport to the 18.x release branch? It fixes a problem with our application on the FreeBSD-CURRENT branch. https://github.com/SerenityOS/serenity/issues/23365

https://github.com/llvm/llvm-project/pull/83103