message: Enables usage of override specifier for MSVC compilers (beginning with 17.0 which is the compiler of Visual Studio 2012)
diff: #ifndef PUGIXML_OVERRIDE
  # if __cplusplus >= 201103
  # define PUGIXML_OVERRIDE override
  +# elif defined(_MSC_VER) && _MSC_VER >= 1700
  +# define PUGIXML_OVERRIDE override
  # else
  # define PUGIXML_OVERRIDE
  # endif
  