nixos: make GIO_EXTRA_MODULES a session variable

Allow applications started by the systemd user session manager to find
their GIO_EXTRA_MODULES.

nixos/modules/programs/dconf.nix

@@ -60,7 +60,7 @@ in
     environment.systemPackages = [ pkgs.dconf ];
 
     # Needed for unwrapped applications
-    environment.variables.GIO_EXTRA_MODULES = mkIf cfg.enable [ "${pkgs.dconf.lib}/lib/gio/modules" ];
+    environment.sessionVariables.GIO_EXTRA_MODULES = mkIf cfg.enable [ "${pkgs.dconf.lib}/lib/gio/modules" ];
   };
 
 }

nixos/modules/services/desktops/gnome/glib-networking.nix

@@ -38,7 +38,7 @@ with lib;
 
     systemd.packages = [ pkgs.glib-networking ];
 
-    environment.variables.GIO_EXTRA_MODULES = [ "${pkgs.glib-networking.out}/lib/gio/modules" ];
+    environment.sessionVariables.GIO_EXTRA_MODULES = [ "${pkgs.glib-networking.out}/lib/gio/modules" ];
 
   };
 

nixos/modules/services/desktops/gvfs.nix

@@ -57,7 +57,7 @@ in
     services.udev.packages = [ pkgs.libmtp.out ];
 
     # Needed for unwrapped applications
-    environment.variables.GIO_EXTRA_MODULES = [ "${cfg.package}/lib/gio/modules" ];
+    environment.sessionVariables.GIO_EXTRA_MODULES = [ "${cfg.package}/lib/gio/modules" ];
 
   };
 

nixos/modules/services/x11/display-managers/gdm.nix

@@ -149,6 +149,7 @@ in
         environment = {
           GDM_X_SERVER_EXTRA_ARGS = toString
             (filter (arg: arg != "-terminate") cfg.xserverArgs);
+          # GDM is needed for gnome-login.session
           XDG_DATA_DIRS = "${gdm}/share:${cfg.sessionData.desktops}/share";
         } // optionalAttrs (xSessionWrapper != null) {
           # Make GDM use this wrapper before running the session, which runs the