[gtk] ci: Update the vulkan build option

[Emmanuele Bassi <ebassi src gnome org>]

commit 6aa66f59cee5b192f16c87d44561c3ca651e4ee0
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Feb 12 17:04:57 2018 +0000

    ci: Update the vulkan build option

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 4aa9388b0f..6454ac1346 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -21,6 +21,6 @@ before_script:
 build:
   stage: build
   script:
-    - meson -Denable-x11-backend=true -Denable-wayland-backend=true -Denable-broadway-backend=true 
-Denable-vulkan=true _build_full
+    - meson -Denable-x11-backend=true -Denable-wayland-backend=true -Denable-broadway-backend=true 
-Denable-vulkan=yes _build_full
     - cd _build_full
     - ninja