Make c10 tests compilable with -Werror (#69711)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/69711
Test Plan: Imported from OSS
Reviewed By: r-barnes
Differential Revision: D32997005
Pulled By: malfet
fbshipit-source-id: 369194051ece9d213b48584ca84e5d76b3794dae
