[gnome-builder] vala: Allow building against libvala-0.40

[Christian Hergert <chergert src gnome org>]

commit 30ff2fa312d1ca2a7334944b394e8505553ad244
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Mon Sep 11 14:45:50 2017 +0200

    vala: Allow building against libvala-0.40

 plugins/vala-pack/meson.build |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plugins/vala-pack/meson.build b/plugins/vala-pack/meson.build
index ebee8cf..9de36b3 100644
--- a/plugins/vala-pack/meson.build
+++ b/plugins/vala-pack/meson.build
@@ -7,6 +7,7 @@ endif
 add_languages('vala')
 
 libvala_options = [
+  ['libvala-0.40', ''],
   ['libvala-0.38', ''],
   ['libvala-0.36', ''],
   ['libvala-0.34', ''],