Amanda 2.6.1 configure faailing to detect GNU tar

I am building 2.6.1 on OpenBSD 4,5. confiugre was fgailing to detect g`GNU
tar properly. so I added the following to my configure arguments:

--with-gnutar=/usr/local/bin/gtar

This is GNU tar:

# /usr/local/bin/gtar --version
tar (GNU tar) 1.22
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by John Gilmore and Jay Fenlason.

But configure is still reporting:

WARNINGS:
  /usr/local/bin/gtar is not GNU tar, so it will not be used.
  /bin/tar is not GNU tar, so it will not be used.

What do I need to do to coerce Amanda into using this?

I need this, as I need to using exclude files on these machines, and I am
failry certain that requires tar, right? These machines do have a native
dump. of course.



-- 
One of the main causes of the fall of the roman empire was that, lacking
zero, they had no way to indicate successful termination of their C
programs.