cogl/onscreen: Pass things as rectangles (and always non-flipped ones)
Two things: cogl_onscreen_queue_damage() assumed EGL style coordinates, while other API did not. The first commit fixes this. The second commit changes to use MtkRectangle
s instead of an int array with carefully placed x,y,width,height. One could also just pass the MtkRegion around, but decided against it due to all places wanting to use it as an array of rectangles, but I could probably be convinced otherwise if there is a reason to pass around the region.