[libstdc++,doc] Tweak links to FSF web site

[Gerald Pfeifer]

Commmitted.

Gerald

2018-09-29  Gerald Pfeifer  <gerald@pfeifer.com>

	* doc/xml/gnu/fdl-1.3.xml: The Free Software Foundation web
	site now uses https. Also omit the unnecessary trailing slash.
	* doc/xml/gnu/gpl-3.0.xml: Ditto.

Index: doc/xml/gnu/fdl-1.3.xml
===================================================================
--- doc/xml/gnu/fdl-1.3.xml	(revision 264709)
+++ doc/xml/gnu/fdl-1.3.xml	(working copy)
@@ -6,7 +6,7 @@
   <simpara>Version 1.3, 3 November 2008</simpara>
   <simpara>
     Copyright © 2000, 2001, 2002, 2007, 2008
-    <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.fsf.org/">Free Software Foundation, Inc.</link>
+    <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.fsf.org">Free Software Foundation, Inc.</link>
   </simpara>
   <simpara>
     Everyone is permitted to copy and distribute verbatim copies of this
Index: doc/xml/gnu/gpl-3.0.xml
===================================================================
--- doc/xml/gnu/gpl-3.0.xml	(revision 264709)
+++ doc/xml/gnu/gpl-3.0.xml	(working copy)
@@ -9,7 +9,7 @@
   </para>
   <para>
     Copyright © 2007 Free Software Foundation, Inc.
-    <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.fsf.org/">http://www.fsf.org/</link>
+    <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.fsf.org">https://www.fsf.org</link>
   </para>
   <para>
     Everyone is permitted to copy and distribute verbatim copies of this license