PyPy compatibility: let unmodified slots be inherited in the standard way (#17837)
Summary:
This is needed to fix a segfault on PyPy 3.6, see https://bitbucket.org/pypy/pypy/issues/2968/segfault-calling-cpyext_tp_new_tuple and https://github.com/pytorch/pytorch/issues/17835
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17837
Differential Revision: D14399408
Pulled By: soumith
fbshipit-source-id: 75328a30018313d3223dd3e3eef9240a416c049b
