Code copied from Guix commit 4c1dff9abeb383ca58dbfcbc27e1bd464d2ad2ea.
List of copyright holders obtained with:

  git log --pretty=format:%an --grep="[Ss]cotch" gnu/packages/maths.scm|sort -u

* inria/tadaam.scm (scotch-6, ptscotch-6): New variables.