This is a source incompatible change for Q_DECLARE_METATYPE(T*),
which now requires T to be fully defined.
The consequences of this are:
* Forward declared types can no longer be declared as a metatype.
(though this is a very uncommon thing to do).
There is a trivial workaround where necessary.
Change-Id: Id74c40088b8c0b466fcd7c55abd616f69acc82c8
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>