* platform integration cmake thing is from kwin
* checkDBusGlobalMenuAvailable() et al are from Qt's upstream
* requires Qt 5.7
* in KXMLGui applications you still get a traditional menu bar in addition to the global menu, it seems it explicitly sets visible true on the menu bar - in VLC it hides its own menu bar.
Upcoming patches will:
* restore and cleanup kappmenu (the kded module that acts as a registrar for Qt apps, so they will actually start exporting their menus)