rumpclient__closenotify
int rumpclient__closenotify(int *, enum rumpclient_closevariant);
if (rumpclient__closenotify(&closemfd,
if (rumpclient__closenotify(&fd, RUMPCLIENT_CLOSE_CLOSE) == -1)
if (rumpclient__closenotify(&newd, RUMPCLIENT_CLOSE_DUP2) == -1)