Fix 0012675: Do not attempt connection to non-existent database

The original fix for 0012675 was incorrect - the patch was applied to the
wrong line of install.php. We should not be attempting to connect to a
specific database that doesn't exist and needs creating.

The proper solution to 0012675 requires more thought and work because
only certain database backends support connections to database servers
without specifying a database to connect to.