QML Debugging: Qt 5 CONFIG+=declarative_debug qml_debug

Pass both arguments to qmake. The assumption being that most
projects will not mix both Qt Quick 1 and Qt Quick 2. In the
case of others, debugging will be enabled only for the first
debugging client that is enabled. This is inline with the
current behaviour where debugging multiple engines is not
supported.

Change-Id: I90cd6c6ff559a3a7519ee3ee10690c0e8135c97b
Reviewed-by: hjk <qthjk@ovi.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>