ssb: Respond to tunnel.endpoints. Patchwork didn't seem to like that we responded to tunnel.isRoom but not this.

src/ssb.h

@@ -883,6 +883,28 @@ int32_t tf_ssb_connection_get_attendant_request_number(tf_ssb_connection_t* conn
 */
 void tf_ssb_connection_set_attendant(tf_ssb_connection_t* connection, bool attendant, int request_number);
 
+/**
+** Register for endpoint change notifications on a connection.
+** @param connection The SHS connection.
+** @param endpoint Whether this connection will be an endpoint.
+** @param request_number The request number on which to send endpoint changes.
+*/
+void tf_ssb_connection_set_endpoint(tf_ssb_connection_t* connection, bool endpoint, int request_number);
+
+/**
+** Get whether we are a potential tunnel endpoint.
+** @param connection The SHS connection.
+** @return True if this is an endpoint connection.
+*/
+bool tf_ssb_connection_is_endpoint(tf_ssb_connection_t* connection);
+
+/**
+** Get the request number used to notify of tunnel endpoint changes.
+** @param connection the SHS connection.
+** @return A request number.
+*/
+int32_t tf_ssb_connection_get_endpoint_request_number(tf_ssb_connection_t* connection);
+
 /**
 ** Clear all attendants from a room.
 ** @param connection The SHS connection.