[clang] [clang-tools-extra] Reland: [clang] NFC: Clear some uses of MemberPointerType::getClass (PR #132317)

[Alexander Kornienko via cfe-commits]

alexfh wrote:

We're also seeing Clang crashes after the original commit, which are not fixed here.

https://github.com/llvm/llvm-project/pull/132317