Remove '-nomake demos' from configure options

Complaining about bad configure arguments was made more strict
in qtbase/1aaeb9538b8f001cee80eef75a15176e0d3910ed

Change-Id: Ia123c7aa63d41373e9720de8ffd5d58a7e4ff485
Reviewed-by: Kai Koehne <kai.koehne@digia.com>