minor fixes in c10d for Windows (#62953)
Summary:
Found out by triggering builds against clang on Windows.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62953
Reviewed By: gchanan
Differential Revision: D30191300
Pulled By: ezyang
fbshipit-source-id: d929119768298084c41d70dbc3a78aacd64fb715
