cmake: Check USB device driver

Check UsbDk device driver. If not found, fall back to libusbK.
If libusbK device driver is not found, bail.

Fix #621

Author: xlz

cmake_modules/FindLibUSB.cmake

@@ -42,8 +42,23 @@ FIND_PATH(LibUSB_INCLUDE_DIRS
 )
 
 SET(LIBUSB_NAME libusb)
-IF(LIBUSB_USE_USBDK)
-  SET(LIBUSB_NAME libusb-usbdk)
+IF(WIN32)
+  INCLUDE(CheckCSourceRuns)
+  CHECK_C_SOURCE_RUNS("#include <windows.h>\nint main(){return !LoadLibraryA(\"libusbK\");}" LIBUSB_WITH_LIBUSBK)
+  CHECK_C_SOURCE_RUNS("#include <windows.h>\nint main(){return !LoadLibraryA(\"UsbDkHelper\");}" LIBUSB_WITH_USBDK)
+
+  IF(LIBUSB_USE_USBDK)
+    SET(LIBUSB_NAME libusb-usbdk)
+  ENDIF()
+
+  IF(LIBUSB_NAME MATCHES ^libusb-usbdk$ AND NOT LIBUSB_WITH_USBDK)
+    MESSAGE(WARNING "UsbDk device driver is not found. Fall back to libusbK.")
+    SET(LIBUSB_NAME libusb)
+  ENDIF()
+
+  IF(LIBUSB_NAME MATCHES ^libusb$ AND NOT LIBUSB_WITH_LIBUSBK)
+    MESSAGE(FATAL_ERROR "No USB device driver is installed.")
+  ENDIF()
 ENDIF()
 
 FIND_LIBRARY(LibUSB_LIBRARIES