bandwidthd for 2.2 full install

Thanks to charliem https://forum.pfsense.org/index.php?topic=78175.msg428321#msg428321 for this patch to make bandwidthd find the right library environment on 2.2 full install.
I also tested on 2.1.4 full install in a VM, as this change does change the way bandwidthd is run in the 2.1.n series - it works.