Enum values should share the same base classes as their defining class.
If this is not the case it may lead to wrong inference results when an
enum member is used - e.g. for the following snippet:

class X(enum.IntEnum):
    one = 1

print([1, 2][X.one])

pylint will detect a "invalid-sequence-index" error as the __index__
method of X.one is not detected.

In Python 3.4+, the module level functions are retrieved with getattr
from a context object, leading to many no-member errors
in Pylint. This patch ensures us that we can retrieve those attributes,
no matter what.