subselect_sj_mat.test: fix test failure on some platforms because of race

of two query plans with identical costs.

mysql-test/r/subselect_sj_mat.result

@@ -86,8 +86,8 @@ a1	a2
 explain extended
 select * from t1i where a1 in (select b1 from t2i where b1 > '0');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t2i	index	it2i1,it2i3	it2i1	9	NULL	5	40.00	Using where; Using index; LooseScan
-1	PRIMARY	t1i	ref	it1i1,it1i3	it1i3	9	test.t2i.b1	1	100.00	Using index
+1	PRIMARY	t2i	index	it2i1,it2i3	it2i1	#	NULL	5	40.00	Using where; Using index; LooseScan
+1	PRIMARY	t1i	ref	_it1_idx	_it1_idx	#	_ref_	1	100.00	Using_where_or_index
 Warnings:
 Note	1003	select `test`.`t1i`.`a1` AS `a1`,`test`.`t1i`.`a2` AS `a2` from `test`.`t1i` semi join (`test`.`t2i`) where ((`test`.`t1i`.`a1` = `test`.`t2i`.`b1`) and (`test`.`t2i`.`b1` > '0'))
 select * from t1i where a1 in (select b1 from t2i where b1 > '0');

mysql-test/t/subselect_sj_mat.test

@@ -70,6 +70,8 @@ select * from t1 where (a1, a2) in (select b1, min(b2) from t2 where b1 > '0' gr
 select * from t1 where (a1, a2) in (select b1, min(b2) from t2 where b1 > '0' group by b1);
 
 # indexed columns
+--replace_column 7 #
+--replace_regex /it1.*/_it1_idx/  /test.t2i.*/_ref_/  /Using index$/Using_where_or_index/ /Using where$/Using_where_or_index/
 explain extended
 select * from t1i where a1 in (select b1 from t2i where b1 > '0');
 select * from t1i where a1 in (select b1 from t2i where b1 > '0');