FileChooser: Allow multiple directory selection on Linux/Zenity

modules/juce_gui_basics/native/juce_linux_FileChooser.cpp

@@ -214,10 +214,13 @@ private:
         }
         else
         {
-            if (isDirectory)  args.add ("--directory");
-            if (isSave)       args.add ("--save");
+            if (isSave)
+                args.add ("--save");
         }
 
+        if (isDirectory)
+            args.add ("--directory");
+
         if (owner.filters.isNotEmpty() && owner.filters != "*" && owner.filters != "*.*")
         {
             StringArray tokens;