Add missing header guards. (#42272)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/42272
Test Plan: Imported from OSS
Reviewed By: IvanKobzarev
Differential Revision: D22835546
Pulled By: AshkanAliabadi
fbshipit-source-id: c880199acaf0ad11c3db4ac9f9f2d000038f98f1
