fix build error

* NAN is not defined on some platform
  * follow the comment on PR

modules/core/test/test_arithm.cpp

@@ -1,5 +1,9 @@
 #include "test_precomp.hpp"
 #include <cmath>
+#ifndef NAN
+#include <limits> // numeric_limits<T>::quiet_NaN()
+#define NAN std::numeric_limits<float>::quiet_NaN()
+#endif
 
 using namespace cv;
 using namespace std;