[libstdc++,doc] Remove extraneous http:// in doc/xml/manual/profile_mode.xml

[Gerald Pfeifer]

This link turned out to be a little http:// heavy after revision
r245277. ;-)

Fixed thusly,
Gerald

2017-02-18  Gerald Pfeifer  <gerald@pfeifer.com>

	* doc/xml/manual/profile_mode.xml: Fix link.

Index: doc/xml/manual/profile_mode.xml
===================================================================
--- doc/xml/manual/profile_mode.xml	(revision 245516)
+++ doc/xml/manual/profile_mode.xml	(working copy)
@@ -26,7 +26,7 @@
   various components at interesting entry/exit points to/from the standard
   library.  Process trace, recognize suboptimal patterns, give advice.
   For details, see the
-  <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://http://ieeexplore.ieee.org/document/4907670/">Perflint
+  <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://ieeexplore.ieee.org/document/4907670/">Perflint
   paper presented at CGO 2009</link>.
   </para>
   <para>