gcc-4.8: Add ObjC and ObjC++ support for Darwin.

Cross-compiling stuff against Mac OS X's CoreFoundation won't work
without ObjC support, and we don't want to compile commandline utilities
only, right?

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/development/compilers/gcc/4.8/default.nix

@@ -352,6 +352,7 @@ stdenv.mkDerivation ({
         ++ optional langAda      "ada"
         ++ optional langVhdl     "vhdl"
         ++ optional langGo       "go"
+        ++ optionals crossDarwin [ "objc" "obj-c++" ]
         )
       )
     }