[wwwdocs] projects/tree-ssa/vectorization.html - update link to GCC Summit Proceedings

[Gerald Pfeifer]

This is a change I found on my disk that dates back more than a year;
I don't recall the trigger back then, but verified it still works and
applied it.

Use the version of the proceedings we've got on our FTP site.  Makes
for a simpler, more stable link.

Gerald

Index: projects/tree-ssa/vectorization.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/projects/tree-ssa/vectorization.html,v
retrieving revision 1.32
diff -u -r1.32 vectorization.html
--- projects/tree-ssa/vectorization.html        29 May 2016 08:11:26 -0000      
1.32
+++ projects/tree-ssa/vectorization.html        2 Jun 2018 12:26:51 -0000
@@ -1524,8 +1524,7 @@
         
         <li>"Loop-Aware SLP in GCC", Ira Rosen, Dorit Nuzman
         and Ayal Zaks, GCC summit, July 2007.
-        <a 
href="https://gcc.gnu.org/wiki/HomePage?action=AttachFile&amp;do=view&amp;target=GCC2007-Proceedings.pdf";>
-        
https://gcc.gnu.org/wiki/HomePage?action=AttachFile&amp;do=view&amp;target=GCC2007-Proceedings.pdf</a></li>
+       <a 
href="ftp://gcc.gnu.org/pub/gcc/summit/2006-GCC-Summit-Proceedings.pdf";>GCC 
Summit 2007 Proceedings</a></li>
 
         <li>"Autovectorization in GCC - two years later", Dorit Nuzman and 
Ayal Zaks, 
         GCC summit, June 2006.