MDEV-5244: Make extended_keys=ON by default in 10.0

- Change the default flag value to ON.
- Update the testcases to be run extended_keys=ON:
  = trivial test result updates
  = If extended_keys setting makes a difference for a testcase, run the testcase 
    with extended_keys=off. There were only a few such cases
- Update to vcol_select_innodb looks like a worse plan but it will be gone in 10.0.

1 files changed, 3 insertions, 0 deletions

diff --git a/mysql-test/r/index_merge_innodb.result b/mysql-test/r/index_merge_innodb.result
index b93d15f7bef..5202c79f3c7 100644
--- a/mysql-test/r/index_merge_innodb.result
+++ b/mysql-test/r/index_merge_innodb.result
@@ -580,9 +580,12 @@ pk1	pk2
 explain select * from t1 where badkey=1 and key1=10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	key1	key1	4	const	100	Using where
+set @tmp_index_merge_ror_cpk=@@optimizer_switch;
+set optimizer_switch='extended_keys=off';
 explain select * from t1 where pk1 < 7500 and key1 = 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	index_merge	PRIMARY,key1	key1,PRIMARY	4,4	NULL	ROWS	Using intersect(key1,PRIMARY); Using where
+set optimizer_switch=@tmp_index_merge_ror_cpk;
 explain select * from t1 where pktail1ok=1 and key1=10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	index_merge	key1,pktail1ok	key1,pktail1ok	4,4	NULL	1	Using intersect(key1,pktail1ok); Using where