install docs and Apple/HP

[Gerald Pfeifer]

In gcc/doc/install.texi we have the following four links (to Apple
and HP sites), all of which are redirected, possibly to pages which
are not useful any longer:

   + http://europe-support.external.hp.com/
   + http://us-support.external.hp.com/
   + http://www.opensource.apple.com/projects/darwin/
   + http://www.opensource.apple.com/tools/cvs/docs.html

Would you mind having a look and updating doc/install.texi on mainline,
3.3, and ideally also 3.2?

Thanks,
Gerald
-- 
Gerald "Jerry"   pfeifer@dbai.tuwien.ac.at   http://www.pfeifer.com/gerald/