Database::RETURN_AFFECTED doesn't actually return number of rows affected due to PDO::MYSQL_ATTR_FOUND_ROWS being enabled

Problem/Motivation

ip_anon module can't figure out how many rows were affected by an update query because Drupal core enables PDO::MYSQL_ATTR_FOUND_ROWS - which means update queries return matched rows rather than affected rows.

Proposed resolution

When a callback needs to run if there were affected rows, we can add a query condition (hostname != 0) to limit the number of matched rows to the affected rows.