Fix incorrect conf_dir variable

[cez81]

In 52f72b961b80e6e47a18b34af8601aeacaf3c534 getOptionalReports() was refactored not to use global $conf_dir variable but instead pass needed variables as parameters. This broke another change, 0888f0195507a5557a8a5656be586505a38a983a, thas was merged the same day.