For a join query with GROUP BY and/or ORDER BY and a view reference
in the FROM list the metadata erroneously showed empty table aliases
and database names for the view columns.



sql/item.h:
  Fixed bug #28898.
  Body of Item_ref::get_tmp_table_item method has been moved
  to item.cc file.
mysql-test/t/metadata.test:
  Updated test case for bug #28898.
sql/item.cc:
  Fixed bug #28898.
  The Item_ref::get_tmp_table_item method has been modified
  to copy pointers to the table alias and database name to the new
  Item_field object created for a field stored in the temporary
  table.
mysql-test/r/metadata.result:
  Updated test case for bug #28898.
sql/sql_select.cc:
  Fixed bug #28898.
  The change_to_use_tmp_fields function has been modified to
  to copy pointers to the table alias and database name from
  the Item_ref objects to the new Item_field objects created
  for fields stored in the temporary table.