In setup.py, also check some submodules of submodules. (#20937)
Summary:
Sometimes users forget using the "--recursive" option when they update submodules. This added check should help expose this issue.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20937
Differential Revision: D15502846
Pulled By: mrshenli
fbshipit-source-id: 34c28a2c71ee6442d16b8b741ea44a18733b1536
