gnustep: remove gdnc service

gdnc is a user process and can't be made into a NixOS module very
easily. It can still be put in the user's login script. According to the
GNUstep documentation it will be started as soon as it is needed.

nixos/modules/module-list.nix

@@ -498,7 +498,6 @@
   ./services/x11/hardware/multitouch.nix
   ./services/x11/hardware/synaptics.nix
   ./services/x11/hardware/wacom.nix
-  ./services/x11/gdnc.nix
   ./services/x11/redshift.nix
   ./services/x11/window-managers/awesome.nix
   #./services/x11/window-managers/compiz.nix

nixos/modules/services/x11/gdnc.nix

@@ -1,31 +0,0 @@
-{ config, lib, pkgs, ... }:
-with lib;
-
-let
-  cfg = config.services.gdnc;
-in {
-  options = {
-    services.gdnc.enable = mkEnableOption "Enable gdnc, the GNUstep distributed notification center";
-  };
-  config = mkIf cfg.enable {
-    assertions = singleton {
-      assertion = config.services.gdnc.enable -> config.services.gdomap.enable;
-      message = "Cannot start gdnc without starting gdomap";
-    };
-    environment.systemPackages = [ pkgs.gnustep.make pkgs.gnustep.base ];
-    systemd.services.gdnc = {
-      path = [ pkgs.gnustep.base ];
-      description = "gdnc: GNUstep distributed notification center";
-      requires = [ "gdomap.service" ];
-      wantedBy = [ "multi-user.target" ];
-      serviceConfig = {
-        ExecStart = ''
-          ${pkgs.gnustep.base}/bin/gdnc -f
-	'';
-        Restart = "always";
-	RestartSec = 10;
-	TimeoutStartSec = "30";
-      };
-    };
-  };
-}