WIP patch provided by Philippe Houdoin

TODO list :
 * Actual management of USB transfers. Needs an USBTransfer class and a worker threadfor each usb_device_handle, should wake up haiku_handle_events (backend asynchronous
function) via a pipe
 * The configuration descriptor is hand-built, while there actually are APIs in Haiku usb kit to get it.

Dynamic detection and enumeration, descriptors are working as expected.