Allow ReflectionPad to accept 0-dim batch sizes. (#39231)
Summary:
Allows ReflectionPad 1D and 2D to accept 0-dim batch sizes.
Related to issues:
* https://github.com/pytorch/pytorch/issues/38115
* https://github.com/pytorch/pytorch/issues/12013
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39231
Reviewed By: ezyang
Differential Revision: D22205717
Pulled By: mruberry
fbshipit-source-id: 6744661002fcbeb4aaafd8693fb550ed53f3e00f
