avfilter/lavfutils: Fix memleak when avformat_find_stream_info() fails

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

libavfilter/lavfutils.c

@@ -46,7 +46,7 @@ int ff_load_image(uint8_t *data[4], int linesize[4],
 
     if ((ret = avformat_find_stream_info(format_ctx, NULL)) < 0) {
         av_log(log_ctx, AV_LOG_ERROR, "Find stream info failed\n");
-        return ret;
+        goto end;
     }
 
     par = format_ctx->streams[0]->codecpar;