Corrects MDB2 login for (at least) Debian

We had a problem with a Debian Wheezy with standard PHP and MDB2, with the main page ending up blank with an error:

[02-Oct-2014 15:02:02 UTC] PHP Fatal error:  Call to undefined method MDB2_Statement_mysql::fetchrow() in /srv/www/maia/login.php on line 150

This small patch corrects it.