Prefer QMetaType over QVariant during a type information query.

Prefer QMetaType over QVariant during a type information query.

As a side effect the patch probably fix special case, when an interface
wants a variant and one of the parameters has to be converted. Before
QVariant::nameToType was returning only builtin types ids.

Change-Id: I473a9bcbd9249acf7c232492fa62c53de3ff5c71
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>