[clang] [Clang][Sema] fix a bug on constraint check with template friend function (PR #90646)

[Krystian Stasiowski via cfe-commits]

sdkrystian wrote:

```cpp
template<typename T, typename U>
concept D = sizeof(T) == sizeof(U);

template<typename T>
struct A
{
    template<typename U, typename V> requires D<U, V>
    static void f();
};

template<typename T, typename U>
struct B
{
    template<typename V>
    struct C
    {
        friend void A<char>::f<T, U>();
    };
};

template struct B<int, int>::C<short>;

extern template void A<char>::f<int, int>(); // crash here
```


https://github.com/llvm/llvm-project/pull/90646