return packet was wrong (port descriptor instead of VM area descriptor),
thus leading to SIGSEGV when calling IOKit's IOFBCreateSharedCursor().
Now this is fixed we can move forward again on graphic mode.
Darwin specific files. The handler does nothing yet.
This needs some improvement. Darwin attaches an IOHIDSystem device to
each human-interface device in the tree: mouse, keyboard, and a few others.
For now we only emulate one IOHIDSystem device.