Don't use anonymous namespace in header. (#21790)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21790
ghimport-source-id: ff648a1e9a1b8627f0742307e2e7810d6445d597
Test Plan: Imported from OSS
Differential Revision: D15827311
Pulled By: ezyang
fbshipit-source-id: 996bfd3a93fcda5934dcc523adae0648cba1c4fa
