VirtualBox port not working with USB

[Graham Menhennitt]

G'day all,

About 6 months ago, the FreeBSD port of VirtualBox was upgraded from 
version 5.0.26 to 5.1.4. The new version didn't work with USB devices 
whereas the old one did. I raised PR 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=212845 at the time. 
Since then, the port has followed the releases of VirtualBox up to 
5.1.14 as of last week (thanks, jkim). However, the same USB problem has 
existed for all that time.

I'm having a go at trying to fix it. But I know almost nothing about the 
VirtualBox source code. So, I'd like some help please. Does anybody here 
have any experience with this. Or any clues as to where I should start 
looking.

At the moment I'm just trying to do diffs between the old and new 
versions, but it's a fairly daunting task. I'm also going to try 
building versions 5.0.32 and 5.1.0 (which never had FreeBSD ports) to 
see whether the breakage was in between them (I presume that it was).

Thanks for any help,

     Graham