Quartz fix: ut2004 makes a 2D window for the splash screen, which sets the screen surface's pixels field. Then we tear down that video mode and create a GL context, and the Quartz target isn't resetting the pixels field to NULL. When you just create a GL window, the structure is memset'd to zero the first time through, so unless you hit ut2004's codepath, you won't see the bug. :) Without this patch, quitting a windowed ut2003/ut2004 game makes the OS dump a warning about a bogus free() to stderr, but it doesn't actually crash. All we need to do is explicitly initialize the current->pixels field.

#ifndef _SDL_SYSMUTEX_C_H_
#define _SDL_SYSMUTEX_C_H_

struct SDL_mutex {
	pth_mutex_t mutexpth_p;
};

#endif /* _SDL_SYSMUTEX_C_H_ */