gnu: discrover: Replace "texlive" with a texlive-union.
* gnu/packages/bioinformatics.scm (discrover)[arguments]: Add build phase
"fix-latex-errors"; add build phase "setenv-HOME".
[inputs]: Add rmath-standalone.
[native-inputs]: Replace "texlive" with a texlive-union consisting of
texlive-fonts-cm, texlive-fonts-amsfonts, texlive-generic-ifxetex,
texlive-latex-doi, texlive-latex-examplep, texlive-latex-hyperref,
texlive-latex-ms, texlive-latex-natbib, texlive-bibtex,
texlive-latex-oberdiek, texlive-latex-pgf, texlive-latex-url,
texlive-latex-verbatimbox, and texlive-latex-xcolor.