Move mainline to autoconf 2.59

[Hans-Peter Nilsson]

> Date: Mon, 8 Mar 2004 19:20:56 -0800 (PST)
> From: Kelley Cook <kelley.cook@sbcglobal.net>

> With a recent patch by Hans-Peter Nilsson, we have unexpectedly moved
> to autoconf 2.58 (which in the FSF version doesn't compute absolute
> path names correctly).
> 
> Separately, libstdc++ recently moved to autoconf 2.59 (along with
> automake 1.8.2)
> 
> Both of these are contrary to documentation with says "autoconf 2.57
> (exactly)."

My apologies, I must've missed that.  In my mind, it was
"autoconf 2.5x".  Sorry.

brgds, H-P