groff 1.25.0.rc3 on Darwin with nixpkgs

[Alexis (surryhill)]

Hi Branden,

when building 1.25.0.rc3 on Darwin using nixpkgs the
contrib/mm/tests/GETST-works.sh fails:

```
  FAIL: contrib/mm/tests/GETST-works.sh
  =====================================

  mmroff: fatal error: "./groff -rRef=1 -z -mm -t -T utf8 -P -cbou 
./contrib/mm/tests/artifacts/use-reference.mm" exited with status 4096
  FAIL contrib/mm/tests/GETST-works.sh (exit status: 1)
```

Please find attached the build log (groff-1.25.0.rc3-nix-build.log.gz).


Best
Alexis

groff-1.25.0.rc3-nix-build.log.gz
Description: application/gzip