process_karaoke_effects: fill from right to left if rotated
process_karaoke_effects: fill from right to left if rotated

This matches VSFilter.

Akemi/libass,ShiftMediaProject/libass,libass/libass,xbmc/libass,MrSmile/libass,astiob/libass,Akemi/libass,astiob/libass,MrSmile/libass,xbmc/libass,ShiftMediaProject/libass,libass/libass,Akemi/libass