bug#45180: Building automake 1.16.3 with autoconf 2.70 fails

[Karl Berry]

    configure:3136: error: The installed version of autoconf does not work.

I don't get that error on GNU/Linux. But I don't think anything
system-dependent is going on, either. I installed autoconf 2.70:

$ autoconf --version
autoconf (GNU Autoconf) 2.70

And then I ran these commands:

tar xf automake-1.16.3.tar.xz 
cd automake-1.16.3
./configure --prefix=/tmp/am
make
make install

And it all worked fine.

    https://savannah.gnu.org/support/index.php?110397 

I can't follow everything there, but for sure, as Zack says, autotest.m4
is not a configure script, so running autoconf on it doesn't make sense.
Zack's other answers also already provide the additional information
that I could think of.

If you have a reproducible recipe starting from the released tarballs,
let us know. --best, karl.