avfilter: fix handing of child context options

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/avfilter.c

@@ -656,11 +656,13 @@ static int process_options(AVFilterContext *ctx, AVDictionary **options,
         av_log(ctx, AV_LOG_DEBUG, "Setting '%s' to value '%s'\n", key, value);
         av_dict_set(options, key, value, 0);
         if ((ret = av_opt_set(ctx->priv, key, value, 0)) < 0) {
+            if (!av_opt_find(ctx->priv, key, NULL, 0, AV_OPT_SEARCH_CHILDREN | AV_OPT_SEARCH_FAKE_OBJ)) {
             if (ret == AVERROR_OPTION_NOT_FOUND)
                 av_log(ctx, AV_LOG_ERROR, "Option '%s' not found\n", key);
             av_free(value);
             av_free(parsed_key);
             return ret;
+            }
         }
 
         av_free(value);