Meta-... shortcuts do not work with the xcb-platform-plugin

If I assign "Meta+Q" to an action it will not trigger as the key stroke is interpreted as plain "Q" in the shortcut handling.

For some reason the xcb-platform-plugin assumes that "Meta" is not supposed to be part of shortcuts, but this used to work with Qt4 on X11 And I did not find the reasoning behind explicitly disabling Meta.

Attached is an example application that has Alt+Q and Meta+Q assigned to closing the window. With Qt4 both actions work, but with Qt5.x only the one with Alt works.

Attached is also a patch that modifies the xcb-platform-plugin to accept Meta as a modifier for shortcuts.

Regards,
Kåre