Simplify EncodedFile.__getattr__

[blueyed]

Ref: https://github.com/pytest-dev/pytest/pull/2557/files#r125854052

[blueyed]

Required for pickling?!

    def test_pickling_and_unpickling_enocded_file():
        # See https://bitbucket.org/pytest-dev/pytest/pull-request/194
        # pickle.loads() raises infinite recursion if
        # EncodedFile.__getattr__ is not implemented properly
        ef = capture.EncodedFile(None, None)
        ef_as_str = pickle.dumps(ef)
>       pickle.loads(ef_as_str)

testing/test_capture.py:1151: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
.tox/py36/lib/python3.6/site-packages/_pytest/capture.py:258: in __getattr__
    return getattr(self.buffer, name)
.tox/py36/lib/python3.6/site-packages/_pytest/capture.py:258: in __getattr__
    return getattr(self.buffer, name)
.tox/py36/lib/python3.6/site-packages/_pytest/capture.py:258: in __getattr__
    return getattr(self.buffer, name)
E   RecursionError: maximum recursion depth exceeded while calling a Python object
!!! Recursion detected (same locals & position)