* develop-olympus:
[ticket/10003] Fixed comment referring to db_tools duplication.
[ticket/10003] Require db_tools.php in database_update.php.
[ticket/10003] Use phpbb_db_tools in database_update.php.
[ticket/10003] Delete the copy of db_tools in database_update.php.
Conflicts:
phpBB/install/database_update.php