SotBE S18: make Howgarth's death result in defeat

It says so in the objectives, but the event was missing.

data/campaigns/Son_Of_The_Black_Eye/scenarios/18_Northern_Alliance.cfg

@@ -701,6 +701,23 @@
         [/message]
     [/event]
 
+    [event]
+        name=die
+
+        [filter]
+            id=Howgarth III
+        [/filter]
+
+        [message]
+            speaker="Kapou'e"
+            message= _ "No! Without him the Northern Alliance will continue to fall apart."
+        [/message]
+
+        [endlevel]
+            result=defeat
+        [/endlevel]
+    [/event]
+
     [event]
         name=victory