io.xml: Update link to groups.google.com.

	* doc/xml/manual/io.xml: Update link to groups.google.com.
	Tweak link description.

From-SVN: r245565

libstdc++-v3/ChangeLog

 2017-02-18  Gerald Pfeifer  <gerald@pfeifer.com>
 
+	* doc/xml/manual/io.xml: Update link to groups.google.com.
+	Tweak link description.
+
+2017-02-18  Gerald Pfeifer  <gerald@pfeifer.com>
+	
 	* doc/xml/manual/profile_mode.xml: Fix link.
 
 2017-02-16  Gerald Pfeifer  <gerald@pfeifer.com>

libstdc++-v3/doc/xml/manual/io.xml

@@ -576,8 +576,8 @@
    <para>
       An instructive thread from comp.lang.c++.moderated delved off into
       this topic starting more or less at
-      <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://groups.google.com/group/comp.std.c++/browse_thread/thread/f87b4abd7954a87/946a3eb9921e382d?q=comp.std.c%2B%2B+binary+iostream#946a3eb9921e382d">this</link>
-      post and continuing to the end of the thread. (The subject heading is "binary iostreams" on both comp.std.c++
+      <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://groups.google.com/forum/#!topic/comp.std.c++/D4e0q9eVSoc">this post</link>
+      and continuing to the end of the thread. (The subject heading is "binary iostreams" on both comp.std.c++
       and comp.lang.c++.moderated.) Take special note of the replies by James Kanze and Dietmar Kühl.
    </para>
     <para>Briefly, the problems of byte ordering and type sizes mean that