Fix Sprite destructor error when not fully constructed.
Fix Sprite destructor error when not fully constructed.

niklaskorz/pyglet,seeminglee/pyglet64,adamlwgriffiths/Pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64,adamlwgriffiths/Pyglet,adamlwgriffiths/Pyglet,niklaskorz/pyglet,seeminglee/pyglet64,niklaskorz/pyglet,niklaskorz/pyglet