ReshapeOp supports empty tensor (#21230)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21230
tsia; we support empty tensor with this diff for reshape operator
Reviewed By: jerryzh168
Differential Revision: D15583356
fbshipit-source-id: 6d44c04e95ca3546509bfb12102e29c878f9a7c7
