Enable the build of tests in ATen/core (#15032)
Summary:
Otherwise they won't build
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15032
Reviewed By: yinghai
Differential Revision: D13409801
Pulled By: houseroad
fbshipit-source-id: 95464aa8f3604835997ba1bb7f3c3e51485d1686
