nat: Add a warning for an important todo item on connection loss

In case we disconnect with some pending operations we will need to
signal the MSC that something is wrong. This could be by sending a
RLSD directly, or a clear command. Another part of the fix is to
respond with a RLC on unknown RLSD messages.

openbsc/src/nat/bsc_nat.c

@@ -492,6 +492,7 @@ static void remove_bsc_connection(struct bsc_connection *connection)
 		if (sccp_patch->bsc != connection)
 			continue;
 
+#warning "TODO: Send a RLSD to the MSC. Or at least a clear command."
 		llist_del(&sccp_patch->list_entry);
 		talloc_free(sccp_patch);
 	}