Fix the compare logic in function `overflows` for MSVC (#15499)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/15497.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15499
Differential Revision: D13547835
Pulled By: soumith
fbshipit-source-id: a674da93bf905a0b81f0cc60449ccb97c2746926
