Autocast wrappers for RNN cell apis (#44296)
Summary:
Should fix https://github.com/pytorch/pytorch/issues/42605.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44296
Reviewed By: izdeby
Differential Revision: D23580447
Pulled By: ezyang
fbshipit-source-id: 86027b693fd2b648f043ab781b84ffcc1f72854d
