bug#67796: Automake is not compatible with older Autoconfs we provide

[Ekaitz Zarraga]

Hi,

We have automake packaged, but it's not compatible with older autoconf 
versions so autoconf is not very usable at this point.

```
Ekaitz@tuxedo ~/projects/nlnet/gcc/libstdc++-v3 (riscv)$ guix shell 
automake autoconf@2.64
Ekaitz@tuxedo ~/projects/nlnet/gcc/libstdc++-v3 (riscv) [env]$ 
autoreconf -vif
autoreconf: Entering directory `.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal --force -I . -I .. -I ../config
configure.ac:74: error: Autoconf version 2.65 or higher is required
/gnu/store/p0c4zj5na8w9hpsp5v5h637wnybx0hb6-automake-1.16.5/share/aclocal-1.16/init.m4:29: 
AM_INIT_AUTOMAKE is expanded from...
configure.ac:74: the top level
autom4te: /gnu/store/n3kxhwi5qdil1vlaq5b6zwyiv7wkrw76-m4-1.4.19/bin/m4 
failed with exit status: 63
aclocal: error: autom4te failed with exit status: 63
autoreconf: aclocal failed with exit status: 63
```

Is this only my thing?