tools/graph2dot: fix use of deprecated *put_count

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

tools/graph2dot.c

@@ -66,7 +66,7 @@ static void print_digraph(FILE *outfile, AVFilterGraph *graph)
                  filter_ctx->name,
                  filter_ctx->filter->name);
 
-        for (j = 0; j < filter_ctx->output_count; j++) {
+        for (j = 0; j < filter_ctx->nb_outputs; j++) {
             AVFilterLink *link = filter_ctx->outputs[j];
             if (link) {
                 char dst_filter_ctx_label[128];