avfilter/src_movie: Fix leak of packet upon error

If allocating the AVFrame to contain a decoded frame fails, the AVPacket
containing the data intended to be decoded leaks. This commit fixes
this.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavfilter/src_movie.c

@@ -344,6 +344,7 @@ static av_cold void movie_uninit(AVFilterContext *ctx)
     }
     av_freep(&movie->st);
     av_freep(&movie->out_index);
+    av_packet_unref(&movie->pkt);
     if (movie->format_ctx)
         avformat_close_input(&movie->format_ctx);
 }