message: videoio: fix GStreamer plugin build
diff: @@ -1769,7 +1769,7 @@ CvResult CV_API_CALL cv_capture_open(const char* filename, int camera_index, CV_
  cap = new GStreamerCapture();
  bool res;
  if (filename)
  - res = cap->open(string(filename));
  + res = cap->open(std::string(filename));
  else
  res = cap->open(camera_index);
  if (res)
  