Allow for registration after GlobalInit (#15876)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15876
Build changes made it so some .so libraries are now registered after GlobalInit is called. Although this shouldn't be common, it also shouldn't be explicitly excluded. These changes allow for late Caffe2 registration, but also warn in that case.
Reviewed By: kuttas
Differential Revision: D13608186
fbshipit-source-id: 0ca7bcd32516d374077db0c2548cf8c28ccdd5f6
