Fix compilation with Visual Studion x64

Author: mariusmuja

src/cpp/flann/util/serialization.h

@@ -89,6 +89,9 @@ BASIC_TYPE_SERIALIZER(unsigned long);
 BASIC_TYPE_SERIALIZER(float);
 BASIC_TYPE_SERIALIZER(double);
 BASIC_TYPE_SERIALIZER(bool);
+#ifdef _MSC_VER
+BASIC_TYPE_SERIALIZER(unsigned __int64);
+#endif