[aur-general] delete libusbx packages

[xantares 09]

The following packages have been replaced by their libusb equivalent (like in the main repo see https://www.archlinux.org/packages/core/x86_64/libusb/) and are useless now since libusbx has been merged back to libusb:

https://aur.archlinux.org/packages/lib32-libusbx/
https://aur.archlinux.org/packages/mingw-w64-libusbx/
https://aur.archlinux.org/packages/mingw32-libusbx/

Regards,
xan