stubtest: fix on windows

[hauntsaninja]

Resolves #4448

Co-authored by: Akuli

[JelleZijlstra]

This does exist in 3.5 on Linux.

[Akuli]

The docs say that it's platform specific before Python 3.6 https://docs.python.org/3/library/time.html

[Akuli]

There might be non-windows systems that lack tm_zone, and those will type check pass and get runtime error. I guess that's preferred over failing type check but working correctly at runtime?

[hauntsaninja]

Yup! Also generally speaking, we don't do a great job of platforms outside of linux, win32, darwin (and up until we got stubtest running on windows, win32 had a lot of room for improvement too). For instance, we run flake8-pyi in typeshed CI and it currently only recognises four sys.platform values: https://github.com/ambv/flake8-pyi/blob/cdd527b601d95da1b5223a6be54ce0c675771b4b/pyi.py#L271 And of course, we'd be receptive to improvements for other platforms if we ever got issues or PRs :-)