[Reland] Optimize code path for adaptive_avg_pool2d when output size is (1, 1) (#44211)
Summary:
Reland of https://github.com/pytorch/pytorch/issues/43986
DO NOT MERGE YET. XLA failure seems real.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44211
Reviewed By: mrshenli
Differential Revision: D23590505
Pulled By: ngimel
fbshipit-source-id: 6ee516b0995bfff6efaf740474c82cb23055d274
