pantheon.wingpanel-with-indicators: fix wrapping

Since #81475 this caused the wrapper to be empty of entries from
wrapGAppsHook because the wrapGAppsHook function doesn't add
them anymore, and was moved to gappsWrapperArgsHook. Instead
of just running that in postBuild it's more future proof to make this
use stdenv.mkDerivation because we want to mess around with the
generic builder.

pkgs/desktops/pantheon/desktop/wingpanel/wrapper.nix

@@ -1,7 +1,8 @@
 { lib
 , wrapGAppsHook
 , glib
-, symlinkJoin
+, stdenv
+, xorg
 , wingpanel
 , wingpanelIndicators
 , switchboard-with-plugs
@@ -15,30 +16,44 @@ let
     if indicators == null then wingpanelIndicators
     else indicators ++ (lib.optionals useDefaultIndicators wingpanelIndicators);
 in
-symlinkJoin {
+stdenv.mkDerivation rec {
   name = "${wingpanel.name}-with-indicators";
 
+  src = null;
+
   paths = [
     wingpanel
   ] ++ selectedIndicators;
 
-  buildInputs = [
+  passAsFile = [ "paths" ];
+
+  nativeBuildInputs = [
     glib
     wrapGAppsHook
-  ] ++ (lib.forEach selectedIndicators (x: x.buildInputs))
+  ];
+
+  buildInputs = lib.forEach selectedIndicators (x: x.buildInputs)
     ++ selectedIndicators;
 
-  # We have to set SWITCHBOARD_PLUGS_PATH because wingpanel-applications-menu
-  # has a plugin to search switchboard settings
-  postBuild = ''
-    make_glib_find_gsettings_schemas
+  dontUnpack = true;
+  dontConfigure = true;
+  dontBuild = true;
 
+  preferLocalBuild = true;
+  allowSubstitutes = false;
+
+  installPhase = ''
+    mkdir -p $out
+    for i in $(cat $pathsPath); do
+      ${xorg.lndir}/bin/lndir -silent $i $out
+    done
+  '';
+
+  preFixup = ''
     gappsWrapperArgs+=(
       --set WINGPANEL_INDICATORS_PATH "$out/lib/wingpanel"
       --set SWITCHBOARD_PLUGS_PATH "${switchboard-with-plugs}/lib/switchboard"
     )
-
-    wrapGAppsHook
   '';
 
   inherit (wingpanel) meta;