Automatically close open handle when no device detected

Prior to this change, libx52_vendor_command would leave the device
handle untouched, even if the joystick was disconnected.

This change will force applications to reconnect to the joystick after
they encounter such a failure.

lib/libx52/x52_control.c

@@ -89,6 +89,14 @@ int libx52_vendor_command(libx52_device *x52, uint16_t index, uint16_t value)
         }
     }
 
+    /* Handle device removal */
+    if (rc == LIBUSB_ERROR_NO_DEVICE) {
+        /* Physical device has likely been disconnected, disconnect the virtual
+         * handle, and report the failure.
+         */
+        (void)libx52_disconnect(x52);
+    }
+
     return _x52_translate_libusb_error(rc);
 }