merge of the fix for bug 33133 to 5.1-opt

INSERT INTO t1 VALUES (1),(2),(3),(4);

CREATE VIEW v1 AS SELECT a,(a + 1) AS y FROM t1;

EXPLAIN EXTENDED SELECT y FROM v1 GROUP BY v1.y;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	Using temporary; Using filesort

Warnings:

Note	1003	select (`test`.`t1`.`a` + 1) AS `y` from `test`.`t1` group by (`test`.`t1`.`a` + 1)

DROP VIEW v1;