cpu_unregister_map_client: fix memory leak.

fix memory leak in cpu_unregister_map_client() and cpu_notify_map_clients().
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

exec.c

@@ -3281,6 +3281,7 @@ void cpu_unregister_map_client(void *_client)
     MapClient *client = (MapClient *)_client;
 
     LIST_REMOVE(client, link);
+    qemu_free(client);
 }
 
 static void cpu_notify_map_clients(void)
@@ -3290,7 +3291,7 @@ static void cpu_notify_map_clients(void)
     while (!LIST_EMPTY(&map_client_list)) {
         client = LIST_FIRST(&map_client_list);
         client->callback(client->opaque);
-        LIST_REMOVE(client, link);
+        cpu_unregister_map_client(client);
     }
 }