QUERY HAS GROUP_BY, ORDER_BY, AND LIMIT

Issue:
------
FORCE INDEX is ignored when a query has GROUP_BY, ORDER_BY,
AND LIMIT.

This problem doesn't occur GROUP BY or ORDER BY is removed.


DDL and Query:
--------------
CREATE TABLE t1 (id INT NOT NULL AUTO_INCREMENT,
                 k INT,
                 PRIMARY KEY(id),
                 KEY idx_k (k));

SELECT * FROM t1 FORCE INDEX (idx_k)
  WHERE k BETWEEN 2 AND 5
  GROUP BY id
  ORDER BY id LIMIT 0,1;

Root cause:
-----------
Due to the presence of GROUP BY optimizer adds clustered
index to the set of possible keys
(see add_group_and_distinct_keys()).

test_if_order_by_key() then decides that "idx_k" can't
provide ordering and that index is excluded from the list of
potential indexes to be used by range optimizer for
ORDER BY. Since the only other option left is the clustered
index, that is chosen.

Solution:
---------
If FORCE INDEX is set use only those indexes to check if
they are relevant for ORDER BY. In this query, range
optimizer won't be called since there is no relevant index
(since "idx_k" doesn't include the column "id").

In 5.7, this was fixed as part of WL#6986.