added stub library for cudev module

in order to make CMake scripts work properly

modules/cudev/src/stub.cpp

@@ -0,0 +1,11 @@
+#include <opencv2/core/cvdef.h>
+
+namespace cv { namespace cudev {
+
+CV_EXPORTS void stubFunc();
+
+}}
+
+void cv::cudev::stubFunc()
+{
+}