https://sources.debian.org/src/libusb/2%3A0.1.12-35/debian/patches/06_bsd.diff/ currently reports the BDS-4-Clause licensing terms, including the problematic advertising clause. However the NetBSD foundation relicensed everything to the BSD-2-Clause in 2008, see https://www.netbsd.org/about/redistribution.html#why2clause (the file has a CVS id from 2009). They also state that "Third parties are encouraged to change the license on any files which have a 4-clause license contributed to the NetBSD Foundation to a 2-clause license" so it would be nice to update the licensing terms of the affected file, to make the life of licensing auditors slightly easier. :D