[Clang] Fix name lookup for dependent bases (#114978)

Currently the following example is a compilation failure: 
```cpp
template<typename T> struct A {
    typedef int M;
    struct B {
      typedef void M;
      struct C;
    };
};

template<typename T> struct A<T>::B::C : A<T> {
    M m; // void or int ?
};
```

According to the point 13.8.3.2

```
A dependent base class is a base class that is a dependent type and is not the current instantiation.
Note 2 : A base class can be the current instantiation in the case of a nested class naming an enclosing class as a base.
```

The base class `A` is the current instantiation, because `C` is a nested
class for an enclosing class `A<T>`, it's is the not-dependent base
class and we need to search the names through its scope.

This patch makes this example compile

0 files changed, 0 insertions, 0 deletions