Fix hard-code cmake target (#37310)
Summary:
Fix https://github.com/pytorch/pytorch/issues/33928. Basically just move the dependency into a new imported target.
I'm not sure whether this modification will affect other parts, please test it throughly.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37310
Differential Revision: D21263066
Pulled By: ezyang
fbshipit-source-id: 7dc38f578d7e9bcb491ef5e122106fb66a33156f
