Get libpciaccess to compile on darwin

The added patch uses the correct byte-conversion functions on Apple systems. The library compiles on darwin but is not yet tested.

svn path=/nixpkgs/trunk/; revision=28881

pkgs/servers/x11/xorg/libpciaccess-apple.patch

@@ -0,0 +1,26 @@
+diff -Naur libpciaccess-0.12.1-orig/src/common_interface.c libpciaccess-0.12.1/src/common_interface.c
+--- libpciaccess-0.12.1-orig/src/common_interface.c	2010-07-12 00:32:05.000000000 -0400
++++ libpciaccess-0.12.1/src/common_interface.c	2011-08-29 00:48:17.000000000 -0400
+@@ -67,6 +67,22 @@
+ # define HTOLE_32(x)   (x)
+ #endif /* Solaris */
+ 
++#elif defined(__APPLE__)
++
++#include <architecture/byte_order.h>
++
++#if __BYTE_ORDER == __BIG_ENDIAN
++# define LETOH_16(x)   OSSwapInt16(x)
++# define HTOLE_16(x)   OSSwapInt16(x)
++# define LETOH_32(x)   OSSwapInt32(x)
++# define HTOLE_32(x)   OSSwapInt32(x)
++#else
++# define LETOH_16(x)   (x)
++# define HTOLE_16(x)   (x)
++# define LETOH_32(x)   (x)
++# define HTOLE_32(x)   (x)
++#endif /* darwin */
++
+ #else
+ 
+ #include <sys/endian.h>

pkgs/servers/x11/xorg/overrides.nix

@@ -47,6 +47,10 @@ in
     buildNativeInputs = [ args.perl ];
   };
 
+  libpciaccess = attrs : attrs // {
+    patches = [ ./libpciaccess-apple.patch ];
+  };
+
   libX11 = attrs: attrs // {
     preConfigure = setMalloc0ReturnsNullCrossCompiling;
     postInstall =