- correct table name shown in EXPLAIN Iindex reference)
 - pointer on freed memmory (reallocation of table name in reusing table entry) can't be used in EXPLAIN
(BUG#1584)


mysql-test/r/derived.result:
  test moved to derived table tests
  added test of BUG#1584
mysql-test/r/subselect.result:
  test moved to derived table tests
mysql-test/t/derived.test:
  test moved to derived table tests
  added test of BUG#1584
mysql-test/t/subselect.test:
  test moved to derived table tests
sql/item.cc:
  layout fix
sql/sql_select.cc:
  correct table name assigned to temporary table field