xlibs: replace occurrences by xorg

This seems to have been confusing people, using both xlibs and xorg, etc.
- Avoided renaming local (and different) xlibs binding in gcc*.
- Fixed cases where both xorg and xlibs were used.
Hopefully everything still works as before.

pkgs/development/libraries/jasper/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, unzip, xlibs, libjpeg }:
+{ stdenv, fetchurl, unzip, xorg, libjpeg }:
 
 stdenv.mkDerivation rec {
   name = "jasper-1.900.1";