shaped-texture: Apply viewport and rotation in right order
When using buffer transforms and viewports together, we currently apply the transformation (read: rotation) first, resulting in wrong buffer coordinates for viewport source rects.
Flip the order in whitch we apply our matrix transformations.
This can be tested e.g. via:
weston-simple-damage --use-viewport --transform=flipped-180
This probably broke in !504 (merged)
Edited by Robert Mader