after merge fix of 577 task (SCRUM, pre commit to be able to merge with static tables optimization fix)
fixed derived tables with subselect inside


mysql-test/r/derived.result:
  test of subselects inside derived tables
mysql-test/t/derived.test:
  test of subselects inside derived tables
mysql-test/t/subselect.test:
  subselect test (not finished)
sql/item.cc:
  after merge fix
sql/item.h:
  after merge fix
sql/item_cmpfunc.h:
  after merge fix
sql/item_subselect.cc:
  after merge fix
sql/item_sum.h:
  after merge fix
sql/mysql_priv.h:
  fixed derived tables with subselect inside
sql/sql_class.h:
  after merge fix
sql/sql_derived.cc:
  fixed derived tables with subselect inside
sql/sql_lex.cc:
  fixed derived tables with subselect inside
sql/sql_lex.h:
  fixed derived tables with subselect inside
sql/sql_parse.cc:
  fixed derived tables with subselect inside
  after merge fix
sql/sql_prepare.cc:
  after merge fix
sql/sql_select.cc:
  after merge fix
  fixed derived tables with subselect inside