Where is the patch that adds android_ver()? At the very least that should be listed as a dependency here.
I don't very much like to have changes to asyncio that can only work in Python 3.6; there's still an upstream version (https://github.com/python/asyncio) that is used to do PyPI releases of asyncio for Python 3.3. I try to keep that in sync with the stdlib on all platforms, otherwise figuring out whether any changes need to be packported is a nightmare.
You might also update the comment somewhere that currently states that reuse_port is not supported on Windows.
PS. It amuses me that each platform apparently has a different way to check (there are three different types of platform checks in the lines you change).