MDEV-6434: Wrong result (extra rows) with ORDER BY, multiple-column index, InnoDB

- Filesort has an optmization where it reads only columns that are 
  needed before the sorting is done.
- When ref(_or_null) is picked by the join optimizer, it may remove parts
  of WHERE clause that are guaranteed to be true.
- However, if we use quick select, we must put all of the range columns into the 
  read set. Not doing so will may cause us to fail to detect the end of the range.

mysql-test/r/order_by_innodb.result

@@ -0,0 +1,13 @@
+drop table if exists t0,t1,t2,t3;
+#
+# MDEV-6434: Wrong result (extra rows) with ORDER BY, multiple-column index, InnoDB
+#
+CREATE TABLE t1 (a INT, b INT, c INT, d TEXT, KEY idx(a,b,c)) ENGINE=InnoDB;
+INSERT INTO t1 (a,c) VALUES
+(8, 9),(8, 10),(13, 15),(16, 17),(16, 18),(16, 19),(20, 21),
+(20, 22),(20, 24),(20, 25),(20, 26),(20, 27),(20, 28);
+SELECT  * FROM t1 WHERE a = 8 AND (b = 1 OR b IS NULL) ORDER BY c;
+a	b	c	d
+8	NULL	9	NULL
+8	NULL	10	NULL
+DROP TABLE t1;