Use the time stamp of the touch event when deliver touch as mouse

diff --git a/src/quick/util/qquickdeliveryagent.cpp b/src/quick/util/qquickdeliveryagent.cpp
index 44255a74f8..fdafff0901 100644
--- a/src/quick/util/qquickdeliveryagent.cpp
+++ b/src/quick/util/qquickdeliveryagent.cpp
@@ -81,6 +81,7 @@ void QQuickDeliveryAgentPrivate::touchToMouseEvent(QEvent::Type type, const QEve
                                  (type == QEvent::MouseButtonRelease ? Qt::NoButton : Qt::LeftButton),
                                  touchEvent->modifiers(), Qt::MouseEventSynthesizedByQt);
     ret.setAccepted(true); // this now causes the persistent touchpoint to be accepted too
+    ret.setTimestamp(touchEvent->timestamp());
     *mouseEvent = ret;
 }
 

qint64 QQuickPathViewPrivate::computeCurrentTime(QInputEvent *event) const
{
    if (0 != event->timestamp())
    {    
        return qint64(event->timestamp());
    }    
    return timer.elapsed();
}

void QQuickPathViewPrivate::handleMouseMoveEvent(QMouseEvent *event)
{
    qint64 currentTimestamp = computeCurrentTime(event);

..........
            qint64 elapsed = currentTimestamp - lastPosTime;
            if (elapsed > 0)
                addVelocitySample(diff / (qreal(elapsed) / 1000));
..........
}