Hack for peerstore_api.c

17:36 < amatus> i think i found the race condition i'm running into with
                peerstore api
17:39 < amatus> there's nothing that actually guarantees that the callback for
                GNUNET_MQ_notify_sent is called before the MQ message handlers
                on the response
17:39 < amatus> or at least my scheduler isn't guaranteeing that
17:43 < amatus> yup, i'm getting handle_iterate_result before
                iterate_request_sent
17:44 < amatus> so when handle_iterate_result is handling
                GNUNET_MESSAGE_TYPE_PEERSTORE_ITERATE_END it calls
                GNUNET_PEERSTORE_iterate_cancel which checks ic->ev to see if
                the iterate request can been sent yet
17:44 < amatus> it thinks it hasn't been sent because iterate_request_sent
                wasn't called yet
17:45 < amatus> so it calls GNUNET_MQ_send_cancel and everything explodes