[PyTorch] Remove unnecessary dispatcher.h include in builtin_function.h (#50314)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50314
It's unused.
ghstack-source-id: 119798800
Test Plan: CI
Reviewed By: ezyang
Differential Revision: D25858900
fbshipit-source-id: 16107acb3df0de18ed16d92f1e2c1b0a72e3e43d
