USB.xs:6:17: error: usb.h: No such file or directory USB.xs: In function 'libusb_get_busses': USB.xs:32: warning: return makes pointer from integer without a cast USB.xs: In function 'libusb_open': USB.xs:37: warning: return makes pointer from integer without a cast USB.xs: In function 'libusb_close': USB.xs:42: error: 'usb_dev_handle' undeclared (first use in this function)