- generic --* options are defined to be booleans, without the
  possibility of having an additional parameter
- -qt and -system options don't exist in the --* form
- --foo=bar options exist only in the --* form

Task-number: QTBUG-55610
Change-Id: Ib0480ac6f479df48045c9de8e854a525862ee363
Reviewed-by: Lars Knoll <lars.knoll@qt.io>