pytorch

d00579da - Revert D18399922: Switch XLA to only override abstract functions

Revert D18399922: Switch XLA to only override abstract functions Test Plan: revert-hammer Differential Revision: D18399922 Original commit changeset: b01761673f51 fbshipit-source-id: 2e19ca58f93dd05be3c3a2a125a154d8288db672