New analyzer: crash using type variable with forward referenced bound in annotation

This was introduced by #6563.

Minimized from a crash in S:

```
from typing import Callable, TypeVar

FooT = TypeVar('FooT', bound='Foo')
class Foo: ...

asdf = lambda x: True    # type: Callable[[FooT], bool]
```
References to `FooT` in method definitions is fine. If `class Foo` is moved above `FooT` the problem is resolved.