treewide: remove aliases in nixpkgs

This makes the command ‘nix-env -qa -f. --arg config '{skipAliases =
true;}'’ work in Nixpkgs.

Misc...

- qtikz: use libsForQt5.callPackage

  This ensures we get the right poppler.

- rewrites:

  docbook5_xsl -> docbook_xsl_ns
  docbook_xml_xslt -> docbook_xsl

diffpdf: fixup

pkgs/applications/virtualization/xen/4.5.nix

@@ -1,5 +1,5 @@
 { stdenv, callPackage, fetchurl, fetchpatch, fetchgit
-, ocamlPackages_4_02
+, ocaml-ng
 , withInternalQemu ? true
 , withInternalTraditionalQemu ? true
 , withInternalSeabios ? true
@@ -258,4 +258,4 @@ callPackage (import ./generic.nix (rec {
       else throw "this xen has no qemu builtin";
   };
 
-})) ({ ocamlPackages = ocamlPackages_4_02; } // args)
+})) ({ ocamlPackages = ocaml-ng.ocamlPackages_4_02; } // args)