more correct parameters in result creation script


mysql-test/create-test-result:
  more correct parameters in result creation script
mysql-test/r/subselect.result:
  test of EXISTS
mysql-test/t/subselect.test:
  test of EXISTS
sql/item_subselect.cc:
  EXISTS type of subselect
sql/item_subselect.h:
  EXISTS type of subselect
sql/sql_class.cc:
  EXISTS type of subselect
sql/sql_class.h:
  EXISTS type of subselect
sql/sql_yacc.yy:
  EXISTS type of subselect