postfix aliases incl. all@ for virtual_alias_maps with MySQL

-- Careful: untested :)
SELECT GOTO
  FROM alias
 WHERE address='%s'
   AND active = '1'
UNION
SELECT GROUP_CONCAT(CASE WHEN active='1' THEN username ELSE NULL END separator ', ')
  FROM vmail
 WHERE DOMAIN='%d'
   AND '%s'='all@%d';