Fix check for windows OS in cheroot.server
Fix check for windows OS in cheroot.server

Check was inverted in:

commit 31806a8d138586f888c6085511e66513767bca69
Author: Sviatoslav Sydorenko <wk@sydorenko.org.ua>
Date:   Sun Apr 8 20:44:16 2018 +0200

    Optimize check for windows OS in cheroot.server

cherrypy/cheroot