change BuildExtension.with_options to return a class not a c-tor (#40121)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/40121
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D22076634
Pulled By: pbelevich
fbshipit-source-id: a89740baf75208065e418d7f972eeb52db9ee3cf
