[clang] [Clang] Fix an assertion in the resolution of perfect matches (PR #140073)

[Alexander Kornienko via cfe-commits]

alexfh wrote:

@cor3ntin the reduced test case for the assertion failure above is: https://gcc.godbolt.org/z/zveexjqW3
```
struct N {
  int field;
};
template <typename It, typename T>
struct B {
  B(It, T);
  template <typename It2>
  B(B<It2, T>);
};
template <typename T>
struct C {
  auto g() { return B<int, T>(0, T{}); }
};
void f() {
  using T = decltype(C<decltype(&N::field)>{}.g());
}
```

https://github.com/llvm/llvm-project/pull/140073