Made it so that AI_CONTROLLER_ALLOW_LEADER_CONTROL's menu item...

...only appears if the leader it's supposed to control is alive.

data/core/macros/ai.cfg

@@ -494,7 +494,10 @@
                 description= _ "Ask $ally_leader.name (leader of side $ally_leader.side) to move here"
                 [show_if]
                     side={CONTROLLER_SIDE}
-                    #TODO: show only if ally leader is alive
+                    [have_unit]
+                        side={CONTROLLED_SIDE}
+                        canrecruit=yes
+                    [/have_unit]
                 [/show_if]
                 [command]
                     {CLEAR_AI_ALWAYS_ASPECT_LEADER_GOAL {CONTROLLED_SIDE} }