[PyTorch] Make tls_local_dispatch_key_set inlineable (#49264)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49264
FLAGS_disable_variable_dispatch had to go, but it looks like the only user was some benchmarks anyway.
ghstack-source-id: 118480532
Test Plan: Small (order of 0.1% improvement) on Internal benchmarks
Reviewed By: smessmer
Differential Revision: D25489030
fbshipit-source-id: 63147bae783e7a45391dd70d86730e48d3e0cafc
