Specify _th_ ops in CUDAUnaryOps macros so they are easier to find. (#37582)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/37582
Test Plan: Imported from OSS
Differential Revision: D21328055
Pulled By: gchanan
fbshipit-source-id: de0939dfdb97ab4dca777e0784fc6225ac31abdc
