fix handling of function attributes. (#28569)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28569
Previously, the inclusion of function attributes would "poison" a
ConcreteModuleType, because we did not have a way of checking whether
they are actually the same function. This PR uses the Python function
object to perform that check. This improves our ability to reuse JIT
types between modules.
Also this PR fixes a bug where we weren't properly adding modules as
attributes when converting from ConcreteType -> JIT type (we were adding
them after the fact--another reason to switch from using `register_x` to
`set_x` during module construction, which is on my to-do list after
this).
Fixes https://github.com/pytorch/pytorch/issues/28559
Test Plan: Imported from OSS
Differential Revision: D18111331
Pulled By: suo
fbshipit-source-id: ec2cccf832d3ddd4cd4d28fe19cb265f1275325a
