AdaCore does not seem to update ASIS for GNAT anymore.

This package is based on the last version available at
https://www.adacore.com/community.

It has been repackaged with:
# mk-origtargz --repack --compression=xz --version=2019 ../asis-gpl-2019-src.tar.gz

 -- Nicolas Boulenguez <nicolas@debian.org>, Mon, 16 Nov 2020 16:34:02 +0100
