Automatically extern C extension modules in torch.package (#74702)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74702
- add flag in constructor.
- add if condition routing to extern c-extension in method `_intern_module`.
- add unit test for the new condition.
Test Plan: Imported from OSS
Reviewed By: PaliC
Differential Revision: D35124731
fbshipit-source-id: a4b7fdf3210e0ad4bfd1ea30fd94595d10405987
(cherry picked from commit 57239a77ae099328025ab2d634e7880bd14a473b)
