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/development/python-modules/mysqlclient/default.nix

@@ -1,11 +1,11 @@
-{ stdenv, buildPythonPackage, fetchPypi, libmysql }:
+{ stdenv, buildPythonPackage, fetchPypi, mysql }:
 
 buildPythonPackage rec {
   pname = "mysqlclient";
   version = "1.3.12";
 
   buildInputs = [
-    libmysql
+    mysql.connector-c
   ];
 
   # Tests need a MySQL database