Use switch --old-log-format to mysqld started by im only in 5.1 and up

mysql-test/mysql-test-run.pl

@@ -2539,7 +2539,10 @@ EOF
 ;
 
     print OUT "nonguarded\n" if $instance->{'nonguarded'};
+    if ( $mysql_version_id >= 50100 )
+    {
       print OUT "log-output=FILE\n" if $instance->{'old_log_format'};
+    }
     print OUT "\n";
   }