optimize max pool 2d (#17418)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17418
Retry of D14181620 this time with CMakeLists.txt changes
Reviewed By: jianyuh
Differential Revision: D14190538
fbshipit-source-id: c59b1bd474edf6376f4c2767a797b041a2ddf742
