Updated link to zlib's home page.

Doc/lib/libzlib.tex

@@ -9,7 +9,7 @@
 For applications that require data compression, the functions in this
 module allow compression and decompression, using the zlib library.
 The zlib library has its own home page at
-\url{http://www.info-zip.org/pub/infozip/zlib/}.  Version 1.1.3 is the
+\url{http://www.gzip.org/zlib/}.  Version 1.1.3 is the
 most recent version as of September 2000; use a later version if one
 is available.  There are known incompatibilities between the Python
 module and earlier versions of the zlib library.
@@ -149,6 +149,5 @@ action is to delete the object.
 
 \begin{seealso}
   \seemodule{gzip}{Reading and writing \program{gzip}-format files.}
-  \seeurl{http://www.info-zip.org/pub/infozip/zlib/}{The
-          zlib library home page.}
+  \seeurl{http://www.gzip.org/zlib/}{The zlib library home page.}
 \end{seealso}