[PATCH] Null terminate connection error message

If the error message provided by the server is too long, this error string may
not be null terminated. Not so sure we can assume the buffer is initialised to
zeros before hand.

--- a/NQ/net_dgrm.c	2006-03-11 23:24:21.000000000 +1030
+++ head/NQ/net_dgrm.c	2006-06-03 17:02:02.000000000 +0930
@@ -1347,6 +1347,7 @@
 	reason = MSG_ReadString();
 	Con_Printf(reason);
 	strncpy(m_return_reason, reason, 31);
+	m_return_reason[31] = 0;
 	goto ErrorReturn;
     }