cmake: do not check for Qt when BUILD_QJDNS is OFF
cmake: do not check for Qt when BUILD_QJDNS is OFF

machinekoder/QtQuickVcp,qtquickvcp/QtQuickVcp,JDSquared/QtQuickVcp,strahlex/QtQuickVcp,psi-im/jdns,psi-im/jdns,bobvanderlinden/QtQuickVcp,bobvanderlinden/QtQuickVcp,machinekoder/QtQuickVcp,qtquickvcp/QtQuickVcp,araisrobo/QtQuickVcp,qtquickvcp/QtQuickVcp,psi-im/jdns,JDSquared/QtQuickVcp,JDSquared/QtQuickVcp,strahlex/QtQuickVcp,bobvanderlinden/QtQuickVcp,qtquickvcp/QtQuickVcp,JDSquared/QtQuickVcp,araisrobo/QtQuickVcp,strahlex/QtQuickVcp,araisrobo/QtQuickVcp,machinekoder/QtQuickVcp,araisrobo/QtQuickVcp,machinekoder/QtQuickVcp