fix: public hdf headers (issue opencv/6016)

modules/hdf/include/opencv2/hdf/hdf5.hpp

@@ -37,16 +37,12 @@
 
 #include <vector>
 
-#include <hdf5.h>
-
-
-
-using namespace std;
 
 namespace cv
 {
 namespace hdf
 {
+using namespace std;
 
 //! @addtogroup hdf5
 //! @{

modules/hdf/src/hdf5.cpp

@@ -34,7 +34,7 @@
 
 #include "precomp.hpp"
 
-
+#include <hdf5.h>
 
 using namespace std;