doc/examples/metadata: use av_dict_iterate

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

doc/examples/metadata.c

@@ -52,7 +52,7 @@ int main (int argc, char **argv)
         return ret;
     }
 
-    while ((tag = av_dict_get(fmt_ctx->metadata, "", tag, AV_DICT_IGNORE_SUFFIX)))
+    while ((tag = av_dict_iterate(fmt_ctx->metadata, tag)))
         printf("%s=%s\n", tag->key, tag->value);
 
     avformat_close_input(&fmt_ctx);