core: Fix handle_events return code on hotplug pipe read error

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
core: Add a new public libusb_get_port_numbers function

This new function replaces the now deprecated libusb_get_port_path function,
as that is the only function operating on a libusb_device which also takes
a libusb_context, which is rather inconsistent.

Note we will keep libusb_get_port_path around in the 1.0.x for the forseeable
future for ABI compatibility reasons, but it should not be used in any new
code.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Examples: Fix use of deprecated libusb_get_port_path

While at it also simplify the path printing in listdevs

Signed-off-by: Hans de Goede <hdegoede@redhat.com>