out-variant for torch.batch_norm_elemt (#27621)
Summary:
Following dicussion with ezyang in https://github.com/pytorch/pytorch/issues/26288
Pull Request resolved: https://github.com/pytorch/pytorch/pull/27621
Differential Revision: D17978858
Pulled By: ezyang
fbshipit-source-id: f843b691a67f1dc48b87ed6a633007d193150cf7
