Enable TensorPipe CUDA sending to self (#50674)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50674
Test Plan: Imported from OSS
Reviewed By: beauby
Differential Revision: D25941964
Pulled By: mrshenli
fbshipit-source-id: b53454efdce01f7c06f67dfb890d3c3bdc2c648f
