Aria and MyISAM in create_internal_tmp_table_from_heap()
(safe, as duplicates are impossible).
This gives a HUGE speed boost!

sql/opt_subselect.cc:
  Fixed problem with wrong recinfo in create_duplicate_weedout_tmp_tabl()
  Tagged the table with 'no_rows' so that when we create the table on disk,
  we only store the index data. This gave us a major speedup!
sql/sql_select.cc:
  create_tmp_table_from_heap() now uses bulk_insert + repair_by_sort
  when creating Aria/MyISAM tables from HEAP tables.
  This gives a HUGE speed boost!
storage/maria/ha_maria.cc:
  Extended bulk_insert() to recreate UNIQUE keys for
  internal temporary tables
storage/maria/ma_open.c:
  Initialize m_info->lock.type properly for temporarly tables
  (needed for start_bulk_insert())
storage/maria/ma_write.c:
  Don't check uniques that are disabled
storage/myisam/ha_myisam.cc:
  Extended bulk_insert() to recreate UNIQUE keys for
  internal temporary tables.