This is a followup to 1071381646 and
e5dbda5abc, which had the downside that
remaining references to these two variables would trigger deprecation
warning during the "Computing Guix derivation" phase of 'guix pull'.
* gnu/packages/tex.scm (texlive-latex-listings, texlive-latex-pgf): Use
plain 'define-public' instead of 'define-deprecated-package'.