SE
 - Add new utility function close_acl_tables() used to commit and close
   the acl tables after reading
 - Add new utility function acl_trans_commit_and_close_tables() used to commit
   and close the acl tables after writing. The function will always try to
   commit since in memory structures have been modified. If the commit fails
   and writes are rollbacked, the memory structures are reloaded from tables
 - Pass flag to write_bin_log() telling if the changes are transactional or
   not and thus the binlog should wait for commit/rollback
 - Remove unused function check_acl_user()