Using newer autoconf in src/cgen directory

[Frank Ch. Eigler]

Hi -

> I have been working to move the src tree at soureware.org to a newer
> version of autoconf.  The reason for this is so that we can, in turn,
> move to a newer version of libtool.  Would it be possible to rebuild the
> configure script in src/cgen with autoconf 2.59?  [...]

Feel free to commit those changes.  cgen is barely worthy of autoconf
anyway, being an interpreted program and all.

- FChE