_fetch_seterr
void _fetch_seterr(struct fetcherr *, int);
#define _ftp_seterr(n) _fetch_seterr(_ftp_errlist, n)
#define _http_seterr(n) _fetch_seterr(_http_errlist, n)
#define _netdb_seterr(n) _fetch_seterr(_netdb_errlist, n)
#define _url_seterr(n) _fetch_seterr(_url_errlist, n)