made FLANN (and dependent on it code) build fine on Windows. Most of the changes are added CV_EXPORTS' into the class declarations and extern variables are turned into external functions (as a nice side effect the variables are now read-only)

modules/flann/src/precomp.hpp

@@ -0,0 +1,18 @@
+#ifndef _OPENCV_FLANN_PRECOMP_HPP_
+#define _OPENCV_FLANN_PRECOMP_HPP_
+
+#include <cstdio>
+#include <cstdarg>
+#include <sstream>
+
+#include "opencv2/flann/dist.h"
+#include "opencv2/flann/index_testing.h"
+#include "opencv2/flann/logger.h"
+#include "opencv2/flann/saving.h"
+#include "opencv2/flann/general.h"
+
+// index types
+#include "opencv2/flann/all_indices.h"
+
+#endif
+