Use libusb_wrap_sys_device() and avoid rescanning the USB bus

It should be possible to open the device in pcscd and just give the file descriptor to libccid.

benefits:

• No USB scanning is required in libccid
• the correct interface is always found on composite devices
• starting a new reader would be faster

Possibly LIBUSB_OPTION_WEAK_AUTHORITY could be used to avoid USB scanning in libusb_init(). See https://github.com/libusb/libusb/pull/925