[ratbox3 svn r26397] Make it more likely that error messages on ssld connections...

[ratbox3 svn r26397] Make it more likely that error messages on ssld connections get through.
When ssld reports a connection closure because of
"Remote host closed the connection" and the connection
is any server or a registered client, try a
read_packet() on the client.
This should mainly help LIBRB_USE_IOTYPE=poll which
iterates over the ready file descriptors in numerical
order, processing the ssld control connection before the
closing data connection.