Don't keep the dummy renderer alive for EGLRenderer's lifetime

At best, it doesn't do anything other than some queue some viewport
changes via SDL_RendererEventWatch(). At worst, it can race with
the render thread and cause trouble.

app/streaming/video/ffmpeg-renderers/eglvid.h

@@ -68,6 +68,4 @@ private:
 
 #define OVERLAY_PARAM_TEXTURE 0
     int m_OverlayShaderProgramParams[1];
-
-    SDL_Renderer *m_DummyRenderer;
 };