-Don't add to IO::Select object until the socket is confirmed to have been created normally

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@1065 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd

xCAT-server-2.0/sbin/xcatd

@@ -263,13 +263,13 @@ if ($inet6support) {
                                      Domain => AF_INET);
 }
 
-  $select->add($socket);
   openlog("xCAT UDP",'','local4');
   unless ($socket) {
     syslog("err","xCAT UDP service unable to open port $port: $!");
     closelog();
     die "Unable to start UDP on $port";
   }
+  $select->add($socket);
   my $data;
   my $part;
   my $sport;