packaging: include windows-curses on Windows
Otherwise the interface degrades to the old hunk selection method on Windows
when ui.tweakdefaults=1. I've been using this for a couple of months without
any issues, other than it seems to toggle off edit mode for the terminal when
run through MSYS. Using cmd.exe seems to work fine.
Differential Revision: https://phab.mercurial-scm.org/D9805