nixos: don't white-list port 5900 in the firewall when x11vnc is enabled

If you want x11vnc to receive TCP connections from the rest of the world,
please add

    networking.firewall.allowedTCPPorts = [ 5900 ];

to /etc/nixos/configuration.nix.

See <http://lists.science.uu.nl/pipermail/nix-dev/2013-November/011997.html>
for the discussion that lead to this.

nixos/modules/services/x11/terminal-server.nix

@@ -42,8 +42,6 @@ in
         Xaccess=${pkgs.writeText "Xaccess" "localhost"}
       '';
 
-    networking.firewall.allowedTCPPorts = [ 5900 ];
-
     systemd.sockets.terminal-server =
       { description = "Terminal Server Socket";
         wantedBy = [ "sockets.target" ];