Error when building autoconf2.1, broken package?

[Carlo B.]

Hello,
I did these actions:
1) Downloaded autoconf2.1-2.13-12-src.tar.bz2
2) Unpack that file.
3) I run this command:

cygport autoconf2.1.cygport all

and this is the output on screen:

>>> Preparing autoconf2.1-2.13-12.x86_64
>>> Unpacking source autoconf-2.13.tar.gz
*** Info: applying patch autoconf2.1-texinfo.patch (-p2):
patching file autoconf.texi
>>> Preparing working source directory
*** Info: applying patch autoconf2.1-2.13-12.cygwin.patch (-p2):
patching file CYGWIN-PATCHES/autoconf2.1.README
>>> Compiling autoconf2.1-2.13-12.x86_64
*** ERROR: could not detect autoconf version; perhaps set AUTOCONF_VERSION?

Have you an idea of the cause of the problem?
I tried to download and rebuild also autoconf2.5 and autoconf2.7 and
they worked fine, only 2.1 fails.
Thank you very much for your time.

Sincerely,

Carlo Bramini.