Updating top-level autoconf to 2.59

[DJ Delorie]

> > newlib/gdb/binutils still uses cvs, though.
> 
> Well, up to you: leave it unmoved or lose the CVS history?  gdb has a
> configure.ac nowadays, bfd doesn't.

It was more of a reminder that you needed to update both repositories.

As for the cvs history, I think the long-term gain of following
conventions exceeds the short term gain of making history more readily
accessible.  The history is still there, just not in the same file.