message: Update cap_gstreamer.cpp
  fixed call open(int id) failed
diff: @@ -613,10 +613,12 @@ int GStreamerCapture::getCaptureDomain() { return CAP_GSTREAMER; }
  */
  bool GStreamerCapture::open(int id)
  {
  + gst_initializer::init();
  +
  if (!is_gst_element_exists("v4l2src"))
  return false;
  std::ostringstream desc;
  - desc << "v4l2src device-name=/dev/video" << id
  + desc << "v4l2src device=/dev/video" << id
  << " ! " << COLOR_ELEM
  << " ! appsink";
  return open(desc.str());
  