print clang tidy output to stderr (#24052)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24052
This will make things show up in the azure pipelines output
Test Plan: Imported from OSS
Differential Revision: D16723846
Pulled By: suo
fbshipit-source-id: d78cbf476be74ccfb28d6e1b21d66b6641d36e26
