Expose iso_node_set_hidden(), to let a node be hidden in RR/ISO or Joliet tree.

src/node.c

@@ -229,6 +229,11 @@ time_t iso_node_get_ctime(const IsoNode *node)
     return node->ctime;
 }
 
+void iso_node_set_hidden(IsoNode *node, int hide_attrs)
+{
+    node->hidden = hide_attrs;
+}
+
 /**
  * Add a new node to a dir. Note that this function don't add a new ref to
  * the node, so you don't need to free it, it will be automatically freed