Replace defunct URL with stable archive.org URL in rbtree.c

The URL for "Sorting and Searching Algorithms: A Cookbook"
by Thomas Niemann has started returning 404, and since we
refer to the page for license terms this replaces the now
defunct link with one to the copy on archive.org.

Author: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/6DED3DEF-875E-4D1D-8F8F-7353D5AF7B79@gmail.com

diff --git a/src/backend/lib/rbtree.c b/src/backend/lib/rbtree.c
index 3b5e5faa9bf5f1bfe6562fc01e6ab296829f91e9..1f0553f914d47f162abee5c01f3060f47799ed88 100644 (file)
--- a/src/backend/lib/rbtree.c
+++ b/src/backend/lib/rbtree.c
@@ -7,9 +7,9 @@
  * This code comes from Thomas Niemann's "Sorting and Searching Algorithms:
  * a Cookbook".
  *
- * See http://www.cs.auckland.ac.nz/software/AlgAnim/niemann/s_man.htm for
- * license terms: "Source code, when part of a software project, may be used
- * freely without reference to the author."
+ * See https://web.archive.org/web/20131202103513/http://www.cs.auckland.ac.nz/software/AlgAnim/niemann/s_man.htm
+ * for license terms: "Source code, when part of a software project, may be
+ * used freely without reference to the author."
  *
  * Red-black trees are a type of balanced binary tree wherein (1) any child of
  * a red node is always black, and (2) every path from root to leaf traverses