Attempt to fix windows build. (#24916)
Summary:
It looks like https://github.com/pytorch/pytorch/pull/24455 broke the windows build, probably an instance of:
https://github.com/pytorch/pytorch/issues/12117.
I don't have a windows machine handy and I'm not sure:
1) what the rules are with dependent constructors
2) if the type is used transitively
but this is a minimal attempt at fixing.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24916
Differential Revision: D16922615
Pulled By: gchanan
fbshipit-source-id: 0dfde84d0c462a14c479eed02ffafb5c4b3c12bb
