Canceled touch event is used while detecting double click event

When a touch event immediately follows a canceled touch event, a double click event is generated for this sequence. 

This occurs for example in the following case:

 - Perform a scroll operation using a two-finger gesture on the touchpad of a chromebook

 - Perform a single click. => This generates a new MotionEvent that is immediately cancelled, followed by the actual MotionEvent. As the two MotionEvent's are generated by the same user input, those two events occur inside a double click detection interval.

Possible solution

Resetting touchMousePressTimestamp inside QQuickWindowPrivate::deliverTouchCancelEvent fixes this issue:

bool QQuickWindowPrivate::deliverTouchCancelEvent(QTouchEvent *event)
{
    ...
    touchMousePressTimestamp = 0;
    ...
}