dont force msvc /Ox flag which can conflict with /RTC1 in debug config (#33164)
Summary:
Relates to https://github.com/pytorch/pytorch/issues/33132
This fix doesn't add full multi-configuration support described in https://github.com/pytorch/pytorch/issues/33132 but at least avoid the error presented in the issue when `CMAKE_BUILD_TYPE=Debug` is used with MSVC.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33164
Differential Revision: D19899727
Pulled By: ezyang
fbshipit-source-id: 28a364d920c4a3fb577c6b484ccd69a133fbcf5d
