Patch from Benoit Pierre:
video: fix clipping handling in SDL_UpperBlitScaled
- honor destination clipping rectangle
- update both destination and source rectangles when clipping source
rectangle to source surface and destination rectangle to destination
clip rectangle
- don't change scaling factors when clipping
N.B.:
- when no scaling is involved (source and destination width/height are
the same), SDL_UpperBlit is used (so SDL_BlitScaled behaves like
SDL_BlitSurface)
- the final destination rectangle after all clipping is performed is
saved back to dstrect (like for SDL_UpperBlit)
61712c5787