ffmpeg media decoder: Fix double free() (and possibly #14394.

Don't call avcodec_close() and then avcodec_free_context().
The latter replaces the former.

http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2ef6dab0a79a9852a92ed80b07f9e32a37530d9e

Change-Id: I346dc8da20a274bcfd901b4a67e612f0f38323b0

src/add-ons/media/plugins/ffmpeg/AVCodecDecoder.cpp

@@ -148,7 +148,7 @@ AVCodecDecoder::~AVCodecDecoder()
 #endif
 
 	if (fCodecInitDone)
-		avcodec_close(fCodecContext);
+		avcodec_free_context(&fCodecContext);
 
 	swr_free(&fResampleContext);
 	free(fChunkBuffer);
@@ -158,7 +158,6 @@ AVCodecDecoder::~AVCodecDecoder()
 	av_free(fRawDecodedPicture);
 	av_free(fRawDecodedAudio->opaque);
 	av_free(fRawDecodedAudio);
-	avcodec_free_context(&fCodecContext);
 	av_free(fDecodedDataBuffer);
 
 	av_frame_free(&fFilterFrame);