xdg-utils: add missing perl dependencies

Or else `xdg-screensaver suspend <WINDOW_ID>` fails with errors like:

  Can't locate Net/DBus.pm in @INC [...]

This increases the closure of xdg-utils from 53 MiB to 119 MiB.

(The issue was found when testing retroarch.)

pkgs/tools/X11/xdg-utils/default.nix

@@ -1,6 +1,6 @@
 { stdenv, fetchurl, fetchFromGitHub
 , file, libxslt, docbook_xml_dtd_412, docbook_xsl, xmlto
-, w3m, gnugrep, gnused, coreutils, xset
+, w3m, gnugrep, gnused, coreutils, xset, perlPackages
 , mimiSupport ? false, gawk ? null }:
 
 assert mimiSupport -> gawk != null;
@@ -13,6 +13,11 @@ let
     rev = "8e0070f17bcd3612ee83cb84e663e7c7fabcca3d";
     sha256 = "15gw2nyrqmdsdin8gzxihpn77grhk9l97jp7s7pr7sl4n9ya2rpj";
   };
+
+  perlPath = with perlPackages; makePerlPath [
+    NetDBus XMLTwig XMLParser X11Protocol
+  ];
+
 in
 
 stdenv.mkDerivation rec {
@@ -39,6 +44,7 @@ stdenv.mkDerivation rec {
     awk()   { ${gawk}/bin/awk       "$@"; }\
     sort()  { ${coreutils}/bin/sort "$@"; }\
     xset()  { ${xset}/bin/xset      "$@"; }\
+    perl()  { PERL5LIB=${perlPath} ${perlPackages.perl}/bin/perl "$@"; }\
     &#' -i "$out"/bin/*
 
     substituteInPlace $out/bin/xdg-open \