move legacy C-API constants into separate files

modules/video/include/opencv2/video/legacy/constants_c.h

@@ -0,0 +1,16 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#ifndef OPENCV_VIDEO_LEGACY_CONSTANTS_H
+#define OPENCV_VIDEO_LEGACY_CONSTANTS_H
+
+enum
+{
+    CV_LKFLOW_PYR_A_READY = 1,
+    CV_LKFLOW_PYR_B_READY = 2,
+    CV_LKFLOW_INITIAL_GUESSES = 4,
+    CV_LKFLOW_GET_MIN_EIGENVALS = 8
+};
+
+#endif // OPENCV_VIDEO_LEGACY_CONSTANTS_H

modules/video/include/opencv2/video/tracking.hpp

@@ -47,14 +47,6 @@
 #include "opencv2/core.hpp"
 #include "opencv2/imgproc.hpp"
 
-enum
-{
-    CV_LKFLOW_PYR_A_READY = 1,
-    CV_LKFLOW_PYR_B_READY = 2,
-    CV_LKFLOW_INITIAL_GUESSES = 4,
-    CV_LKFLOW_GET_MIN_EIGENVALS = 8
-};
-
 namespace cv
 {