clang format reducer.cpp (#40876)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40876
clang format reducer.cpp
ghstack-source-id: 106980050
Test Plan: unit test
Differential Revision: D22321422
fbshipit-source-id: 54afdff206504c7bbdf2e408928cc32068e15cdc
