Upstream libusb does not support FreeBSD. (Even though it does support OpenBSD, NetBSD and even Haiku.)
All tests passed on my FreeBSD machine!
Always use system libusb on FreeBSD
Wait, it segfaults when listing devices as root (with access to /dev/usb/*)…
Add FreeBSD libusb_get_port_numbers workarounds
Okay, now everything works great :)