Pass the right signal index in visualadaptormodel proxy meta-object

Pass the right signal index in visualadaptormodel proxy meta-object

For QMetaObject::activate(), the index must be relative to the
class's own signals (excluding non-signal methods).
For QMetaObjectBuilder, the notifier index must be relative to the
class's own methods.

Change-Id: I22f55d1fc55d56c997135dc78f51b710b37bb01a
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>