[arch-general] libusbx as replacement for libusb

[Alexandre Ferrando]

As the subject says, with the move from libusb to libusbx I've
encountered an issue when upgrading my system with testing enabled:

:: Starting full system upgrade...
:: Replace libusb with testing/libusbx? [Y/n] y
resolving dependencies...
looking for inter-conflicts...
error: failed to prepare transaction (could not satisfy dependencies)
:: usbmuxd: requires libusb>=1.0.8

usbmuxd is required by libimobiledevice, which turns to be required by
upower ( and others, but only upower in my system)

Any idea on how to proceed from this point?