Since the Terminal Server is a single thread, let's not block for long
periods of time trying to send bytes to a client (e.g. send the badip.msg
file contents to a client with a blocked IP address), effectively DoSing the
terminal server.

This should address the problem reported via IRC:
<theviper4> │Apr  9 15:38:11 viper-bbs synchronet: term Terminal Server timeout(outcom) 0000 0000
<theviper4> │Apr  9 15:38:35 viper-bbs synchronet: term Terminal Server !ERROR 110 sending on socket 39
<theviper4> │Apr  9 15:38:35 viper-bbs synchronet: term Terminal Server !ERROR 32 sending on socket 39
<theviper4> │Apr  9 15:38:35 viper-bbs synchronet: term Terminal Server !ERROR 32 sending on socket 39
<theviper4> │Apr  9 15:38:36 viper-bbs synchronet: term 0039 Telnet !CLIENT BLOCKED in ip.can: 117.95.153.33

Also, make the outcom timeout error message more helpful (e.g. include the
sock descriptor of the client) and don't use the old rioctl() function
here any more.