Use a separate callback to indicate EOS instead of renderFrame()

app/streaming/video/ffmpeg-renderers/vdpau.cpp

@@ -476,11 +476,6 @@ void VDPAURenderer::renderOverlay(VdpOutputSurface destination, Overlay::Overlay
 
 void VDPAURenderer::renderFrame(AVFrame* frame)
 {
-    if (frame == nullptr) {
-        // End of stream - nothing to do for us
-        return;
-    }
-
     VdpStatus status;
     VdpVideoSurface videoSurface = (VdpVideoSurface)(uintptr_t)frame->data[3];