> Do Readline and LAPACK show up in ‘guix gc --references $(guix build
> apl)’?  If they don’t, you can remove them.

LAPACK doesn’t show up, but this line appears in the logs when it’s
omitted:

LApack.cc:410:2: warning: #warning liblapack not found or not installed. ⌹ will not work. [-Wcpp]

> As for gettext, please check in the log whether some of its commands are
> actually run.

I know nearly nothing about Gettext.  The only bits that seem relevant:

checking for msgfmt... /nix/store/1v42xk9j5hzbgxbh21pdp97ccd244hvl-gettext-0.18.3/bin/msgfmt
checking for gmsgfmt... /nix/store/1v42xk9j5hzbgxbh21pdp97ccd244hvl-gettext-0.18.3/bin/msgfmt
checking for xgettext... /nix/store/1v42xk9j5hzbgxbh21pdp97ccd244hvl-gettext-0.18.3/bin/xgettext
checking for msgmerge... /nix/store/1v42xk9j5hzbgxbh21pdp97ccd244hvl-gettext-0.18.3/bin/msgmerge