Add a renderer selection option for macOS

There are numerous conflicting reports about which Mac renderer works best (even on the same systems!). I give up, just let the users figure it out.

app/streaming/video/ffmpeg.h

@@ -86,7 +86,7 @@ private:
                                IFFmpegRenderer::InitFailureReason* failureReason,
                                std::function<IFFmpegRenderer*()> createRendererFunc);
 
-    static IFFmpegRenderer* createHwAccelRenderer(const AVCodecHWConfig* hwDecodeCfg, int pass);
+    static IFFmpegRenderer* createHwAccelRenderer(const AVCodecHWConfig* hwDecodeCfg, PDECODER_PARAMETERS params, int pass);
 
     bool initializeRendererInternal(IFFmpegRenderer* renderer, PDECODER_PARAMETERS params);