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.

## Makefile.am for SDL using the XBIOS video driver

noinst_LTLIBRARIES = libvideo_xbios.la
libvideo_xbios_la_SOURCES = $(XBIOS_SRCS)

# The SDL XBIOS video driver sources
XBIOS_SRCS = 	\
	SDL_xbios.c	\
	SDL_xbios.h