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/version-management/git-and-tools/cgit/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchurl, openssl, zlib, asciidoc, libxml2, libxslt
-, docbook_xml_xslt, pkgconfig, luajit
+, docbook_xsl, pkgconfig, luajit
 , gzip, bzip2, xz
 , python, wrapPython, pygments, markdown
 }:
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ pkgconfig ] ++ [ python wrapPython ];
   buildInputs = [
-    openssl zlib asciidoc libxml2 libxslt docbook_xml_xslt luajit
+    openssl zlib asciidoc libxml2 libxslt docbook_xsl luajit
   ];
   pythonPath = [ pygments markdown ];