BUG#16893: Crash in test 'fulltext_order_by'

Fixed that fulltext query + union results in unexpected behaviour.


sql/item_func.h:
  Remove access to table object from cleanup() as the table object
  may have been dropped earlier (In case of temporary tables or of
  close_thread_tables() is run before cleanup())
  This fixed a bug with access to already freed memory
sql/sql_base.cc:
  Reset variables used by fulltext

sql/item_func.h

@@ -1057,9 +1057,6 @@ public:
     {
       ft_handler->please->close_search(ft_handler);
       ft_handler=0;
-      if (join_key)
-	table->file->ft_handler=0;
-      table->fulltext_searched=0;
     }
     if (concat)
     {

sql/sql_base.cc

@@ -988,6 +988,8 @@ TABLE *open_table(THD *thd,const char *db,const char *table_name,
   table->status=STATUS_NO_RECORD;
   table->keys_in_use_for_query= table->keys_in_use;
   table->used_keys= table->keys_for_keyread;
+  table->file->ft_handler=0;
+  table->fulltext_searched=0;
   if (table->timestamp_field)
     table->timestamp_field_type= table->timestamp_field->get_auto_set_type();
   DBUG_ASSERT(table->key_read == 0);