TorchScript Serialization for dynamic LSTM module
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/25877
Test Plan: Imported from OSS
Reviewed By: jianyuh
Differential Revision: D17275746
Pulled By: jamesr66a
fbshipit-source-id: db2f38ddd99f02ccb4fb754fa1c1e6cad4425fa8
