Do not double compile generated files (#36417)
Summary:
Bazel puts generated files in its private hermetic builds, but for some reason also searches for files in `torch/csrcs/*/generated/` folders.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36417
Test Plan: Use the same folder to compile pytorch using cmake and bazel
Differential Revision: D20987580
Pulled By: malfet
fbshipit-source-id: 36d15ba3ce0d0c7ea923ddef902bd500f2578430
