[libstdc++,doc] adjust link to www.oracle.com

[Gerald Pfeifer]

I applied the patch below.  Given a number of fixes in libstdc++/doc
I've applied recently, can one of you please regenerate the HTML pages 
in the next days?

Thanks,
Gerald

2018-09-30  Gerald Pfeifer  <gerald@pfeifer.com>
 
	* doc/xml/manual/messages.xml: Switch link to www.oracle.com
	to https.

Index: doc/xml/manual/messages.xml
===================================================================
--- doc/xml/manual/messages.xml	(revision 264721)
+++ doc/xml/manual/messages.xml	(working copy)
@@ -541,7 +541,7 @@ void test01()
   <biblioentry>
       <title>
 	<link xmlns:xlink="http://www.w3.org/1999/xlink"
-	      xlink:href="http://www.oracle.com/technetwork/java/api/index.html">
+	      xlink:href="https://www.oracle.com/technetwork/java/api/index.html">
 	API Specifications, Java Platform
 	</link>
       </title>