Port replication_pad1d to ATen (#15507)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15507
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15485
port replication_pad1d
Reviewed By: ezyang
Differential Revision: D13531920
fbshipit-source-id: dcd64ebd2c24b7431996231b8d5addfb600b1072
