Make QWindowCompositor render when surfaces move around

Change-Id: I1f363238232c145941940fe203b110f8855d8c26
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Calling damage on a surface from the compositor api doesn't make sense

It will not cause the damaged signal to be emitted

Change-Id: Ifb8265811d432d80bd6d84469d5c673b62d65290
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>