Bug 8997

While trying to build the target in xserver/GL/apple aglGlx.c cannot be compiled. The reason obviously 
comes from the unknown type definition of __GLXdrawablePrivate, which is used before '*'. This one is 
defined in xserver/hw/dmx/glxProxy/glxdrawable.h.

So it seems to be necessary to add

	typedef struct __GLXdrawablePrivateRec __GLXdrawablePrivate;

to xserver/GL/apple/aglGlx.c. Still another error continues to exist:

	aglGlx.c:117: error: parse error before ‘__glDDXScreenInfo’
	aglGlx.c:117: warning: type defaults to ‘int’ in declaration of ‘__glDDXScreenInfo’
	aglGlx.c:118: warning: initialization makes integer from pointer without a cast
	aglGlx.c:119: warning: excess elements in scalar initializer
	aglGlx.c:119: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:120: warning: excess elements in scalar initializer
	aglGlx.c:120: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:121: warning: excess elements in scalar initializer
	aglGlx.c:121: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:122: warning: excess elements in scalar initializer
	aglGlx.c:122: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:123: warning: excess elements in scalar initializer
	aglGlx.c:123: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:124: warning: excess elements in scalar initializer
	aglGlx.c:124: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:125: warning: excess elements in scalar initializer
	aglGlx.c:125: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:126: warning: excess elements in scalar initializer
	aglGlx.c:126: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:127: warning: excess elements in scalar initializer
	aglGlx.c:127: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:129: warning: excess elements in scalar initializer
	aglGlx.c:129: warning: (near initialization for ‘__glDDXScreenInfo’)
	aglGlx.c:129: warning: data definition has no type or storage class

A __GLXscreenInfo is defined in xserver/hw/dmx/glxProxy/glxscreens.h, but with different components. 
This seems to correspond with these reports:

http://lists.freedesktop.org/archives/xorg/2006-March/014248.html
http://lists.freedesktop.org/archives/xserver-commit/2005-December/002095.html

and might come from a patch described here by its author: http://lwn.net/Articles/173833/. So it seems  
that the __GLXscreenInfo based code needs to become updated to make use of __GLXscreen. And these 
seem to quite a lot lines of C code!