codecvt.xml: Move link to "UTF-8 and Unicode FAQ" to https.

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

From-SVN: r264547

libstdc++-v3/ChangeLog

+2018-09-25  Gerald Pfeifer  <gerald@pfeifer.com>
+
+	* doc/xml/manual/codecvt.xml: Move link to "UTF-8 and Unicode FAQ"
+	to https.
+
 2018-09-24  Gerald Pfeifer  <gerald@pfeifer.com>
 
 	* doc/xml/manual/policy_data_structures_biblio.xml: Update link

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

@@ -673,7 +673,7 @@ codecvt usage.
   <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>