Bug#25471090: MYSQL USE AFTER FREE

fix another similar line

followup for 7828ba0d

sql-common/client.c

@@ -1636,7 +1636,7 @@ MYSQL_DATA *cli_read_rows(MYSQL *mysql,MYSQL_FIELD *mysql_fields,
       else
       {
 	cur->data[field] = to;
-        if (len > (ulong) (end_to - to))
+        if (to + len > end_to)
         {
           free_rows(result);
           set_mysql_error(mysql, CR_MALFORMED_PACKET, unknown_sqlstate);