[PyTorch] Reapply D25547962: Make tls_local_dispatch_key_set inlineable (reapply) (#49763)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49763
This was reverted because it landed in a stack together with
D25542799 (https://github.com/pytorch/pytorch/commit/9ce1df079f6ea90dd4b7f9aa12a1a78d51a8b204), which really was broken.
ghstack-source-id: 119063016
Test Plan: CI
Reviewed By: ezyang
Differential Revision: D25685959
fbshipit-source-id: 514d8076eac67c760f119cfebc2ae3d0ddcd4e04
