Revert D34554432: Back out "Revert D34524207: [pytorch][PR] remove _s_where"
Test Plan: revert-hammer
Differential Revision:
D34554432 (https://github.com/pytorch/pytorch/commit/9c03c6163f068726b6463ea53dee45b8831dd8db)
Original commit changeset: 2f3601d3d426
Original Phabricator Diff: D34554432 (https://github.com/pytorch/pytorch/commit/9c03c6163f068726b6463ea53dee45b8831dd8db)
fbshipit-source-id: db434750f44c6e6ec545a248c462d8fdcbefbaf8
(cherry picked from commit 866d4d0c795edd7ef519925683b5e57dd9b116ad)
