Bluez5 support for QBluetoothDeviceDiscovery

Task-number: QTBUG-32085
Change-Id: I31ae0dc9f0d09f3979797eb95eb87ed7bd181ae3
Reviewed-by: Oleg Shparber <trollixx@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>