L S8 Give Harper a loyal overlay in Liberty's final scenario

He's been a silver-crowned hero until this scenario, and in
the final scenario he's still loyal with dialogue if he dies,
so make him easily visible to the player.

data/campaigns/Liberty/scenarios/08_Glory.cfg

@@ -428,6 +428,12 @@
 
         {UNMAKE_HERO Harper}
 
+        # He's still a loyal unit with dialogue when he dies
+        [unit_overlay]
+            id=Harper
+            image=misc/loyal-icon.png
+        [/unit_overlay]
+
         [message]
             speaker=Baldras
             message= _ "There it is. The stronghold of Halstead."