[modules][caffe2/aten] Fix `#include` inside of namespace error (#35302)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35302
This is an error in modular builds.
Test Plan: CI
Reviewed By: igorsugak
Differential Revision: D20591224
fbshipit-source-id: 44e8e1be9e54b94f7b54be6bdeb4260a763667ce
