I'm sorry if your understanding of valid hostnames, acceptable by GNU projects, is
two decades old but this project happens to be the only one that assumes there
exists a finite list of valid hostnames without using pattern matching.
Using and a hostname of armv7a-
hardfloat-linux-gnu, with the notable exception of libgpg-error, I have been able
to compile and install all other GNU utilities included the core set of Gentoo
Linux, whether via the package's giving configure script or by use of autoreconf.
Hare are just a few of such GNU packages that I have personally been able to build
and install using the hostname "armv7a-hardfloat-linux-gnu":
coreutils-8.25
bash-4.3_p42
diffutils-3.3
findutils-4.6.0
grep-2.25
groff-1.22.3
gzip-1.8
tar-1.29
glibc-2.23
less-483
gawk-4.1.3
which-2.21
nettle-3.2
glibc-2.23
gcc-5.3.0
readline-6.3_p8
nano-2.5.3
The only other GNU package that doesn't compile for me is autogen. But that's due
to a lack of cross-compile support. It otherwise builds just fine natively on
armv7a-hardfloat-linux-gnu.
I would appreciate it if you could provide a specific GNU package using autotools
that you assert should fail to support such a hostname, other than this one, so
that I may provide a build log demonstrating that it indeed does.