workaround libusb bug in `libusb_free_device_list(ptr, 1)`

[diablodale]

libusb_free_device_list(ptr, 1) does not handle the scenario of having null entries in the device list. It will errantly stop its unref walk of the list thinking it has reached the terminating null. libusb/libusb#1287

Fix now in my fork of Xlink. Will auto link to the commit below.

[tormodvolden]

The question is why would there be a null entry in this list (other than the terminating null - it is a null-terminated list). The code in usb_host.cpp looks fine, it retrieves the list, iterates over it and frees it without modifying it.

Can you please use an assert instead of "continue" here?

XLink/src/pc/protocols/usb_host.cpp

Line 126 in d209b7e

if(devs[i] == nullptr) continue;

[tormodvolden]

I was looking in the wrong file. wrap_libusb.hpp is a lot more scary.

[diablodale]

@tormodvolden, do you have a bug to report? If so, please open a new bug with: description, setup, repro steps, actual results, and expected results.