On Mac OS X 10.4 (Tiger) at least (the Mac OS X SDKs for Mac OS X 10.2.8 and 10.3.9 have the same set 
of header files, minus the new /usr/include/i386/endian.h) it seems to be necessary to include 
machine/endian.h instead of sys/endian.h, which does not exist. My simple patch to achieve this is:

*** X11R7.1/xserver/GL/glx/indirect_dispatch_swap.c.orig	2006-09-25 19:23:56.000000000 
+0200
--- X11R7.1/xserver/GL/glx/indirect_dispatch_swap.c	2006-09-27 12:06:41.000000000 +0200
***************
*** 36,42 ****
--- 36,46 ----
  #define bswap_32 __swap32
  #define bswap_64 __swap64
  #else
+ #ifdef __APPLE__
+ #include <machine/endian.h>
+ #else
  #include <sys/endian.h>
+ #endif
  #define bswap_16 bswap16
  #define bswap_32 bswap32
  #define bswap_64 bswap64

Five files need this patch to compile:

xserver/GL/glx/indirect_dispatch_swap.c
xserver/GL/glx/indirect_program.c
xserver/GL/glx/indirect_texture_compression
xserver/GL/glx/indirect_util.c
xserver/GL/glx/swap_interval.c