Make avfilter_graph_add_filter() returns AVERROR(ENOMEM) in case of

failed reallocation, rather than just -1.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22878 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavfilter/avfiltergraph.c

@@ -40,7 +40,7 @@ int avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
                                 sizeof(AVFilterContext*) * ++graph->filter_count);
 
     if (!graph->filters)
-        return -1;
+        return AVERROR(ENOMEM);
 
     graph->filters[graph->filter_count - 1] = filter;