[libstdc++,doc] doc/xml/manual/codecvt.xml: Move link to "UTF-8 and Unicode FAQ" to https

[Gerald Pfeifer]

Committed.

Gerald

2018-09-25  Gerald Pfeifer  <gerald@pfeifer.com>

	* doc/xml/manual/codecvt.xml: Move link to "UTF-8 and Unicode FAQ"
	to https.

Index: doc/xml/manual/codecvt.xml
===================================================================
--- doc/xml/manual/codecvt.xml	(revision 264546)
+++ doc/xml/manual/codecvt.xml	(working copy)
@@ -673,7 +673,7 @@
   <biblioentry>
       <title>
 	<link xmlns:xlink="http://www.w3.org/1999/xlink"
-	      xlink:href="http://www.cl.cam.ac.uk/~mgk25/unicode.html">
+	      xlink:href="https://www.cl.cam.ac.uk/~mgk25/unicode.html">
       UTF-8 and Unicode FAQ for Unix/Linux
 	</link>
       </title>