Fix WGL when WGL_EXT_extensions_string is not implemented.
Fix WGL when WGL_EXT_extensions_string is not implemented.

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