ftpd now eventually times out if a ftp client does:

ftpd now eventually times out if a ftp client does:
pasv
list
and then crashes.
The timeout should only apply the the accept(), so that transfers can
take as long as necessary to complete.
Thanks to Theo for moving toolong() to extern.h so that it can be used
in ftpd.c as well as in ftpcmd.y.