Add flag for dynamo+ddp optimizations (#1221)
Summary:
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1221
Add a flag that can be used to turn dynamo+ddp optimizations on. This
will be used to compare how dynamo+ddp performs with and without the
additional graph break strategy for improving dynamo+ddp
compute/communication overlap.
Test Plan: Imported from OSS
Reviewed By: xuzhao9
Differential Revision: D39976005
Pulled By: xuzhao9
fbshipit-source-id: cc58800a5aff68bdf997e325983100dad4ff7c0e
