Fix leak in avfilter_graph_add_filter().

In case of reallocation failure the pointer to the original filter
array was lost. The correct behavior seems to just keep the old array
and count.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22905 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavfilter/avfiltergraph.c

@@ -36,13 +36,13 @@ void avfilter_graph_destroy(AVFilterGraph *graph)
 
 int avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
 {
-    graph->filters = av_realloc(graph->filters,
-                                sizeof(AVFilterContext*) * ++graph->filter_count);
-
-    if (!graph->filters)
+    AVFilterContext **filters = av_realloc(graph->filters,
+                                           sizeof(AVFilterContext*) * (graph->filter_count+1));
+    if (!filters)
         return AVERROR(ENOMEM);
 
-    graph->filters[graph->filter_count - 1] = filter;
+    graph->filters = filters;
+    graph->filters[graph->filter_count++] = filter;
 
     return 0;
 }