dropout symbolic_script should respect the training flag (#20760)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20760
ghimport-source-id: eb667c3549a03a2fc01ffa0a2d3bc7e3a29b78e0
Reviewed By: jamesr66a
Differential Revision: D15486511
Pulled By: suo
fbshipit-source-id: 56ae930a01b0f6f4305a2a745135d4529b4a1ca0