mate.marco: fix cross build

pkgs/desktops/mate/marco/default.nix

@@ -34,11 +34,11 @@ stdenv.mkDerivation rec {
     pkg-config
     gettext
     itstool
+    libxml2 # xmllint
     wrapGAppsHook3
   ];
 
   buildInputs = [
-    libxml2
     libcanberra-gtk3
     libgtop
     libXdamage
@@ -53,10 +53,11 @@ stdenv.mkDerivation rec {
 
   postPatch = ''
     substituteInPlace src/core/util.c \
-      --replace-fail 'argvl[i++] = "zenity"' 'argvl[i++] = "${zenity}/bin/zenity"'
+      --replace-fail 'argvl[i++] = "zenity"' 'argvl[i++] = "${lib.getExe zenity}"'
   '';
 
   env.NIX_CFLAGS_COMPILE = "-I${glib.dev}/include/gio-unix-2.0";
+  env.ZENITY = lib.getExe zenity;
 
   enableParallelBuilding = true;