The sources included several bundled json libraries in thirdparty/. These are
available separately in Debian, so these were removed from the source tarball,
with a patch in debian/patches/ directing the build to use those instead of the
bundled copies.

The spec documents in doc/specifications contain non-dfsg information, so I
exclude those. They're only documentation, so removing these doesn't break
anything:

  https://lintian.debian.org/tags/license-problem-non-free-RFC-BCP78

 -- Dima Kogan <dkogan@debian.org>, Sat, 21 May 2022 16:12:56 -0700
