Fixed UNION fields type/length detecting

mysql-test/r/union.result:
  new results with max union field length detecting
  type conversion tests
mysql-test/t/union.test:
  type conversion tests
sql/field.h:
  field converion support
sql/item.cc:
  fixed printing field of internal temporary table of SELECT (reference from HAVING clause)
  layout fix
  new item for storing field type
sql/item.h:
  new item for storing field type
sql/item_subselect.cc:
  new subquery item length/dec detecting
sql/mysql_priv.h:
  we do not need pre-inited tables and fields
sql/sql_base.cc:
  we do not need double fix_fielding
sql/sql_class.h:
  we do not need double fix_fielding
sql/sql_derived.cc:
  preparing moved before temporary table creation
sql/sql_lex.h:
  we do not need pre-inited tables and fields
  new lists to store fields types and fields of temporary table
sql/sql_parse.cc:
  we do not need pre-inited tables and fields
sql/sql_prepare.cc:
  we do not need pre-inited tables and fields
sql/sql_select.cc:
  we do not need pre-inited tables and fields
  support mysql_select call from derived tables after it preparing (in derived table routing)
  support of crreating temporary table fields from Item_type_holder
sql/sql_select.h:
  we do not need pre-inited tables and fields
sql/sql_union.cc:
  we do not need pre-inited tables and fields
  check of columns number in union moved to prepare()
  prepering of SELECTS moved before temporary table creation, fixed union columns type/length detecting
sql/sql_update.cc:
  we do not need pre-inited tables and fields

sql/sql_update.cc

@@ -461,7 +461,7 @@ int mysql_multi_update(THD *thd,
 		    conds, 0, (ORDER *) NULL, (ORDER *)NULL, (Item *) NULL,
 		    (ORDER *)NULL,
 		    options | SELECT_NO_JOIN_CACHE | SELECT_NO_UNLOCK,
-		    result, unit, select_lex, 0);
+		    result, unit, select_lex);
   delete result;
   DBUG_RETURN(res);
 }