[gnome-games/wip/exalm/lint] ci: Lint with vala-lint

[Alexander Mikhaylenko <alexm src gnome org>]

commit 04b154f20833d203c5411d6b8f6f29065ed55a9b
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Tue Jan 28 20:27:18 2020 +0500

    ci: Lint with vala-lint

 .gitlab-ci.yml           | 6 ++++++
 build-aux/vala-lint.conf | 2 ++
 2 files changed, 8 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e0ffa4aa..d8f436ca 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -39,3 +39,9 @@ stop_review:
 
 nightly:
   extends: '.publish_nightly'
+
+lint:
+  image: valalang/lint:latest
+  stage: .pre
+  script:
+    - io.elementary.vala-lint -c build-aux/vala-lint.conf src plugins
diff --git a/build-aux/vala-lint.conf b/build-aux/vala-lint.conf
new file mode 100644
index 00000000..a8e60925
--- /dev/null
+++ b/build-aux/vala-lint.conf
@@ -0,0 +1,2 @@
+[Checks]
+use-of-tabs=off