message: core: fix unresolved symbols from utils::fs
diff: #include <errno.h>
  #endif
  +#endif // OPENCV_HAVE_FILESYSTEM_SUPPORT
  +
  namespace cv { namespace utils { namespace fs {
  #ifdef _WIN32
  @@ -80,6 +82,8 @@ cv::String join(const cv::String& base, const cv::String& path)
  return result;
  }
  +#if OPENCV_HAVE_FILESYSTEM_SUPPORT
  +
  bool exists(const cv::String& path)
  {
  CV_INSTRUMENT_REGION()
  @@ -511,6 +515,14 @@ cv::String getCacheDirectory(const char* sub_directory_name, const char* configu
  return cache_path;
  }
  -}}} // namespace
  -
  +#else
  +#define NOT_IMPLEMENTED CV_ErrorNoReturn(Error::StsNotImplemented, "");
  +CV_EXPORTS bool exists(const cv::String& /*path*/) { NOT_IMPLEMENTED }
  +CV_EXPORTS void remove_all(const cv::String& /*path*/) { NOT_IMPLEMENTED }
  +CV_EXPORTS bool createDirectory(const cv::String& /*path*/) { NOT_IMPLEMENTED }
  +CV_EXPORTS bool createDirectories(const cv::String& /*path*/) { NOT_IMPLEMENTED }
  +CV_EXPORTS cv::String getCacheDirectory(const char* /*sub_directory_name*/, const char* /*configuration_name = NULL*/) { NOT_IMPLEMENTED }
  +#undef NOT_IMPLEMENTED
  #endif // OPENCV_HAVE_FILESYSTEM_SUPPORT
  +
  +}}} // namespace
  