- if table is temporary it's not crash-safe so we declare it
non-transactional (saves trnman calls, REDO/UNDO log writing,
and fixes the assertion failure at the first line of trnman_destroy()).


storage/maria/ha_maria.cc:
  if table is not transactional, no need to create a transaction:
  - it saves trnman calls (mutex locks etc)
  - it saves REDO and UNDO log writing
  - it closes a bug: if this is a temporary table, external_lock(F_RD|WRLCK)
  is not always paired with external_lock(F_UNLCK), which confuses the
  transaction logic in external_lock. As temp tables are not crash-safe
  and so not transactional in this Maria version, we skip transactions
  and de-confuse. Note that maria_lock_database(F_UNLCK) is
  properly called, so if the transaction logic moves from external_lock()
  to maria_lock_database() (probably TODO), transactional temp tables
  will be possible.
storage/maria/ma_create.c:
  temporary tables cannot be crash-safe as they are dropped at restart
storage/maria/maria_def.h:
  comment