Fixed an error in the creation of REF access method for materialized

subquery execution, where the the REF buffer format was mistaken to
be in record format instead of key format. The error was that the null
byte for all fields of the record was in the front of the buffer,
and not before each field data.

sql/item_subselect.cc

@@ -3957,8 +3957,6 @@ subselect_hash_sj_engine::make_unique_engine()
   Item_iterator_row it(item_in->left_expr);
   /* The only index on the temporary table. */
   KEY *tmp_key= tmp_table->key_info;
-  /* Number of keyparts in tmp_key. */
-  uint tmp_key_parts= tmp_key->key_parts;
   JOIN_TAB *tab;
 
   DBUG_ENTER("subselect_hash_sj_engine::make_unique_engine");

sql/sql_select.cc

@@ -7925,7 +7925,7 @@ bool TABLE_REF::tmp_table_index_lookup_init(THD *thd,
                                     use that information instead.
                                  */
                                  cur_ref_buff + null_count,
-                                 null_count ? key_buff : 0,
+                                 null_count ? cur_ref_buff : 0,
                                  cur_key_part->length, items[i], value);
     cur_ref_buff+= cur_key_part->store_length;
   }