Start an asynchronous accept.

template<
    typename SocketService,
    typename AcceptHandler>
void async_accept(
    basic_socket< protocol_type, SocketService > & peer,
    AcceptHandler handler);

template<
    typename SocketService,
    typename AcceptHandler>
void async_accept(
    basic_socket< protocol_type, SocketService > & peer,
    endpoint_type & peer_endpoint,
    AcceptHandler handler);