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

[Alexander Kornienko via cfe-commits]

alexfh wrote:

Reduced test case: https://gcc.godbolt.org/z/7xxfsj4vv

```
struct A {
  template <class T> A(T);
};
struct C;
template <class T> void d(void (T::*)());
void f(A);
void g() { f(d<C>); }
```

Please revert or fix soon. Thanks!

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