v1.3.1: Enabling inplace relu

Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/28710

Test Plan: Imported from OSS

Differential Revision: D18146120

Pulled By: z-a-f

fbshipit-source-id: d8f0982f5a2ae35f7deb34e67cdb64be700a9d6c