Bug#891640: arctica-greeter: Fails to build with vala 0.40

[Jeremy Bicha]

Package: arctica-greeter
Version:  1.7.0-1
Severity: serious
User: pkg-gnome-maintainers at lists.alioth.debian.org
Usertags: vala-0.40
Tags: buster sid patch

arctica-greeter fails to build from source with vala 0.37.91 which is
currently in experimental and will be uploaded to unstable soon.

You can find a build log from Ubuntu 18.04 Alpha at
https://launchpad.net/~jbicha/+archive/ubuntu/vala40/+build/14327075

See my merge proposal at
https://github.com/ArcticaProject/arctica-greeter/pull/9

Also, could you please add debian/source/include-binaries
with this content:

debian/theme-debian-logo-v9.png
debian/theme-debian-logo-bare.png

(Its absence upset my build tools while I was testing this fix)

On behalf of the Debian GNOME Team,
Jeremy Bicha