message: winrt: fix build
diff: #ifndef OPENCV_HAVE_FILESYSTEM_SUPPORT
  # if defined(__EMSCRIPTEN__) || defined(__native_client__)
  /* no support */
  +# elif defined WINRT
  + /* not supported */
  # elif defined __ANDROID__ || defined __linux__ || defined _WIN32 || \
  defined __FreeBSD__ || defined __bsdi__
  # define OPENCV_HAVE_FILESYSTEM_SUPPORT 1
  