SQL_SELECT::test_quick_select

The crash was caused by an incomplete cleanup of JOIN_TAB::select
during the filesort of rows for GROUP BY clause inside a subquery.
Queries where a quick index access is replaced with filesort was
was affected. For example:

  SELECT 1 FROM
    (SELECT COUNT(DISTINCT c1) FROM t1
       WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x

Quick index access related data in the SQL_SELECT::test_quick_select
function was inconsistent after an incomplete cleanup.
This function has been completed to prevent crashes in the
SQL_SELECT::test_quick_select function.


mysql-test/include/mix1.inc:
  Add test case for bug #44290.
mysql-test/r/innodb_mysql.result:
  Add test case for bug #44290.
sql/sql_select.cc:
  Bug #44290: explain crashes for subquery with distinct in
              SQL_SELECT::test_quick_select
  
  Quick index access related data in the SQL_SELECT::test_quick_select
  function was inconsistent after an incomplete cleanup.
  This function has been completed to prevent crashes in the
  SQL_SELECT::test_quick_select function.