fix for set_icon crashing with PyObjC 2.2
fix for set_icon crashing with PyObjC 2.2

theblacklion/pyglet,oktayacikalin/pyglet,oktayacikalin/pyglet,mammadori/pyglet,theblacklion/pyglet,theblacklion/pyglet,mammadori/pyglet,mammadori/pyglet,oktayacikalin/pyglet,theblacklion/pyglet,theblacklion/pyglet,mammadori/pyglet,oktayacikalin/pyglet,oktayacikalin/pyglet