message: Fixed several issues found by static analysis, GStreamer backend
diff: @@ -1224,7 +1224,11 @@ Ptr<IVideoCapture> cv::createGStreamerCapture(int index)
  class CvVideoWriter_GStreamer : public CvVideoWriter
  {
  public:
  - CvVideoWriter_GStreamer() { init(); }
  + CvVideoWriter_GStreamer()
  + : pipeline(0), source(0), encodebin(0), file(0), buffer(0), input_pix_fmt(0),
  + num_frames(0), framerate(0)
  + {
  + }
  virtual ~CvVideoWriter_GStreamer() CV_OVERRIDE { close(); }
  virtual bool open( const char* filename, int fourcc,
  @@ -1232,7 +1236,6 @@ public:
  virtual void close();
  virtual bool writeFrame( const IplImage* image ) CV_OVERRIDE;
  protected:
  - void init();
  const char* filenameToMimetype(const char* filename);
  GstElement* pipeline;
  GstElement* source;
  @@ -1245,22 +1248,6 @@ protected:
  double framerate;
  };
  -/*!
  - * \brief CvVideoWriter_GStreamer::init
  - * initialise all variables
  - */
  -void CvVideoWriter_GStreamer::init()
  -{
  - pipeline = NULL;
  - source = NULL;
  - encodebin = NULL;
  - file = NULL;
  - buffer = NULL;
  -
  - num_frames = 0;
  - framerate = 0;
  -}
  -
  /*!
  * \brief CvVideoWriter_GStreamer::close
  * ends the pipeline by sending EOS and destroys the pipeline and all
  @@ -1282,17 +1269,19 @@ void CvVideoWriter_GStreamer::close()
  //wait for EOS to trickle down the pipeline. This will let all elements finish properly
  GstBus* bus = gst_element_get_bus(pipeline);
  GstMessage *msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, (GstMessageType)(GST_MESSAGE_ERROR | GST_MESSAGE_EOS));
  - if (GST_MESSAGE_TYPE(msg) == GST_MESSAGE_ERROR)
  + if (!msg || GST_MESSAGE_TYPE(msg) == GST_MESSAGE_ERROR)
  {
  CV_WARN("Error during VideoWriter finalization\n");
  - return;
  - }
  -
  if(msg != NULL)
  {
  gst_message_unref(msg);
  g_object_unref(G_OBJECT(bus));
  }
  + return;
  + }
  +
  + gst_message_unref(msg);
  + g_object_unref(G_OBJECT(bus));
  status = gst_element_set_state (pipeline, GST_STATE_NULL);
  if (status == GST_STATE_CHANGE_ASYNC)
  