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/tools/vulkan-validation-layers/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchFromGitHub, cmake, python3, vulkan-headers, vulkan-loader,
-  glslang, pkgconfig, x11, libxcb, libXrandr, wayland }:
+  glslang, pkgconfig, xlibsWrapper, libxcb, libXrandr, wayland }:
 
 stdenv.mkDerivation rec {
   name = "vulkan-validation-layers-${version}";
@@ -13,7 +13,7 @@ stdenv.mkDerivation rec {
   };
 
   nativeBuildInputs = [ pkgconfig ];
-  buildInputs = [ cmake python3 vulkan-headers vulkan-loader x11 libxcb libXrandr wayland ];
+  buildInputs = [ cmake python3 vulkan-headers vulkan-loader xlibsWrapper libxcb libXrandr wayland ];
   enableParallelBuilding = true;
 
   cmakeFlags = [ "-DGLSLANG_INSTALL_DIR=${glslang}" ];