Back out "[reland] Skip OpenMP Thread when OMP_NUM_THREADS is 1" (#36198)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36198
Original commit changeset: 4476a810dfe7
With the previous diff, when user sets KMP_AFFINITY, it will be ignored when OMP_NUM_THREADS is 1. That could cause performance regression.
Test Plan: n/a
Reviewed By: ilia-cher
Differential Revision: D20909628
fbshipit-source-id: 5738f99aa61072337146257a68189d3d03ad39f7
