Fix pbxt suite to keep the same opti9misation it was before.

mysql-test/suite/pbxt/r/subselect.result

@@ -1483,7 +1483,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 Warnings:
 Note	1003	select `test`.`t1`.`s1` AS `s1`,(not(<in_optimizer>(`test`.`t1`.`s1`,<exists>(<index_lookup>(<cache>(`test`.`t1`.`s1`) in t2 on s1 checking NULL where (`test`.`t2`.`s1` < 'a2') having trigcond(<is_not_null_test>(`test`.`t2`.`s1`))))))) AS `s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2')` from `test`.`t1`
 drop table t1,t2;
-create table t2 (a int, b int);
+create table t2 (a int, b int not null);
 create table t3 (a int);
 insert into t3 values (6),(7),(3);
 select * from t3 where a >= all (select b from t2);

mysql-test/suite/pbxt/t/subselect.test

@@ -925,7 +925,7 @@ drop table t1,t2;
 #
 # correct ALL optimisation
 #
-create table t2 (a int, b int);
+create table t2 (a int, b int not null);
 create table t3 (a int);
 insert into t3 values (6),(7),(3);
 select * from t3 where a >= all (select b from t2);