Problem: Plug two 8-port USB hubs in a chain, add a HID device to second hub: hidapi returns empty string for path.

This was an old signal11 issue signal11/hidapi#301 and I think we still have it. Over in node-hid land (node-hid/node-hid#417), someone was experiencing this problem and had a good test showing both hidapitester and node-hid being able to get a path when the device is plugged in at one leaf of the USB tree but not at the other.

I think the issue happens at Line 464 of hidapi/mac/hid.c and I think it's because io_string_t is 512 characters and MacOS USB paths are already > 200 chars if you have just a single external USB hub.

I'm looking into finding definitions of io_string_t and IORegistryEntryGetPath() to see what our options are.

(The reason why I specify 8-port hubs above is those are implemented as two 4-port hubs, meaning the external USB tree look can look like: hub->hub->hub->hub->device, depending on where you plug what into what)