[wwwdocs] gcc-4.3/porting_to.html -- fix link into libstdc++ manual

[Gerald Pfeifer]

Applied, and while I was at it, also changed the link text from
"here" to "libstdc++ manual".

Gerald


Index: gcc-4.3/porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.3/porting_to.html,v
retrieving revision 1.13
diff -u -r1.13 porting_to.html
--- gcc-4.3/porting_to.html	14 Nov 2015 20:53:58 -0000	1.13
+++ gcc-4.3/porting_to.html	25 Feb 2017 15:36:44 -0000
@@ -314,7 +314,9 @@
   </tr>
 </table>
 
-<p>For future reference, available headers are listed <a href="https://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt01ch03s02.html">here</a>.
+<p>For future reference, available headers are listed in the <a
+href="https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_headers.html">libstdc++
+manual</a>.
 </p>
 
 <p>An example.</p>