Fix a bunch of obvious memory leaks at termination

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

src/xmpp/presence.c

@@ -83,6 +83,12 @@ presence_sub_requests_init(void)
     sub_requests_ac = autocomplete_new();
 }
 
+void
+presence_sub_requests_destroy(void)
+{
+    autocomplete_free(sub_requests_ac);
+}
+
 void
 presence_handlers_init(void)
 {