Binding to a tiny part of libusb.

For a more complete binding, have a look at the more complete and more advanced ocaml-usb.

I wrote this alternate binding:

in order to experiment more in depth with Ctypes;
and because I needed something more portable than ocaml-usb: this one is working on Windows, which was not the case of ocaml-usb when I started this project.

Dependency

Obviously, libusb must installed before compilation. pkg-config is used in order to locate the library during compilation.

On Debian-like systems: apt install libusb-1.0-0-dev

On cygwin, I used mingw64 OCaml installation. This is why I installed mingw64-x86_64-libusb1.0 package.