* Handle licences starting with a digit

cabal has a devscript that parses a json file (containing SPDX licences)
and returns a number of of Haskell data constructors.

There have been problems when the SPDX short identifier starts with
a digit (e.g. “0BSD”), as that would generate an data constructor
starting with a digit, which is not valid Haskell.
The way to handle such occourrences was in an ad-hoc basis.

This patch prepends “N_” to the beginning of every SPDX licence starting
with a digit, future-proofing the script.

* Regenerate licence files

Useless since we are going to have to do it again before a release,
needed to make CI green (“Check that diff is clean”).