Add check for x64 Python before setup (#17707)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/17657.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17707
Differential Revision: D14346705
Pulled By: ezyang
fbshipit-source-id: 5daafacdb99eb9a9c6517263d10f20c79f920d24
