__rb_change_child
__rb_change_child(node, child, parent, root);
__rb_change_child(node, tmp, parent, root);
__rb_change_child(node, successor, tmp, root);
__rb_change_child(victim, new, parent, root);
__rb_change_child(old, new, parent, root);
__rb_change_child(node, child, parent, root);
__rb_change_child(node, tmp, parent, root);
__rb_change_child(node, successor, tmp, root);
__rb_change_child(victim, new, parent, root);
__rb_change_child(old, new, parent, root);