Remove friend dependency on ClassType in InterfaceType (#25617)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25617
This was causing some build issues if you included c10 but not torch
Test Plan: Imported from OSS
Differential Revision: D17173352
Pulled By: suo
fbshipit-source-id: 8b6f65b6cdefea716598dec2909bbeb511f881b5
