decoder/ffmpeg: fix double free bug
From the avformat_open_input() API documentation: "Note that a user-supplied AVFormatContext will be freed on failure." https://bugs.musicpd.org/view.php?id=4607
This commit is contained in:
From the avformat_open_input() API documentation: "Note that a user-supplied AVFormatContext will be freed on failure." https://bugs.musicpd.org/view.php?id=4607