bug#52979: Modular texlive has problems finding fonts

[Jelle Licht <jlicht@fsfe.org>]

As discussed on #guix on IRC, several folks including myself ran into
issues getting the following some-file.tex:

--8<---------------cut here---------------start------------->8---
\documentclass[11pt]{article}
\begin{document}
Hello friends
\end{document}
--8<---------------cut here---------------end--------------->8---

... to typeset with the following manifest.scm:
--8<---------------cut here---------------start------------->8---
(specifications->manifest
 '("texlive-base"
   "texlive-fonts-ec"
   "texlive-amsfonts"
   "texlive-fira"
   "texlive-inconsolata"))
--8<---------------cut here---------------end--------------->8---

... with command: 
`guix shell --pure coreutils grep sed gawk -m manifest.scm -- pdflatex some-file

Note that the monolithic texlive seems to work:
`guix shell --pure coreutils grep sed gawk texlive -- pdflatex some-file'

On IRC, rekado /w strace identified that texlive does not seem to be
entering the subdirectory containing the font files, as it seems to be
loading texlive-bin's texmf.cnf, instead of the one generated by
`(@ (guix profiles) texlive-configuration)'.

It seems some of the talks in the guix-maintenance repository can
currently also not be built for the same or similar reason.