add an option to record time spent waiting for GIL (#30842)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30842
We'd like to profile the time spent on GIL acqusiition to debug
performance issues.
Test Plan: Unit tests pass.
Differential Revision: D18837590
fbshipit-source-id: 925968f71c5fb96b8cd93f1eab4647602d2617d1
