support modules as parameters in generic functions

Note: if you are reporting a wrong signature of a function or a class in
the standard library, then the typeshed tracker is better suited
for this report: https://github.com/python/typeshed/issues

Please provide more information to help us understand the issue:

• Are you reporting a bug, or opening a feature request?

I think this is a bug (the behaviour is consistent with other kind of objects)

• Please insert below the code you are checking with mypy,
  or a mock-up repro if the source is private. We would appreciate
  if you try to simplify your case to a minimal repro.

import typing
T = typing.TypeVar('T')
def same(obj: T) -> T:
    return obj
add = same(3).__add__
TypeVar = same(typing).TypeVar

• What is the actual behavior/output?

minimal.py:6: error: Module has no attribute "TypeVar"

• What is the behavior/output you expect?

[no errors]

• What are the versions of mypy and Python you are using?
  Do you see the same issue after installing mypy from Git master?

0.650

• What are the mypy flags you are using? (For example --strict-optional)

[mypy]
disallow_untyped_defs = True

Iniziare eseguendo l'esempio minimal.py con la configurazione mypy segnalata e verificare che non si verifichi l'errore «Module has no attribute "TypeVar"». Nell'issue non sono indicati né un file sorgente né un test; tracciare come vengono gestiti i risultati delle funzioni generiche quando l'argomento è un modulo, quindi aggiungere una copertura che mostri il comportamento previsto senza errori.