fixed cleanup of result object of subqueries. (BUG#8125)

mysql-test/r/subselect.result:
  cleaning up of results of subselects test
mysql-test/t/subselect.test:
  cleaning up of results of subselects test
sql/item_subselect.cc:
  call result object cleupup on engine cleunup
sql/sql_class.cc:
  added cleanup of select_max_min_finder_subselect
sql/sql_class.h:
  added cleanup of select_max_min_finder_subselect

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 659d67eaf37..16186b1a6d3 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -1127,6 +1127,7 @@ void subselect_single_select_engine::cleanup()
   DBUG_ENTER("subselect_single_select_engine::cleanup");
   prepared= optimized= executed= 0;
   join= 0;
+  result->cleanup();
   DBUG_VOID_RETURN;
 }
 
@@ -1135,6 +1136,7 @@ void subselect_union_engine::cleanup()
 {
   DBUG_ENTER("subselect_union_engine::cleanup");
   unit->reinit_exec_mechanism();
+  result->cleanup();
   DBUG_VOID_RETURN;
 }
 
@@ -1142,6 +1144,10 @@ void subselect_union_engine::cleanup()
 void subselect_uniquesubquery_engine::cleanup()
 {
   DBUG_ENTER("subselect_uniquesubquery_engine::cleanup");
+  /*
+    subselect_uniquesubquery_engine have not 'result' assigbed, so we do not
+    cleanup() it
+  */
   DBUG_VOID_RETURN;
 }