Fix use of c10::guts::apply (#18159)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18159
In some instances, the call to forward could clash with std::forward. Fully qualify it to make sure it gets the right one
Reviewed By: ezyang
Differential Revision: D14512189
fbshipit-source-id: 6242607dbe54fcdb93229c1a4aaee8b84a88caa1
