[mutter] gitlab-ci: Use G_SLICE=always-malloc in tests

[Marco Trevisan <marcotrevi src gnome org>]

commit e3d3df985f3133ced360d9cb148ff1beaa81df7b
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Thu May 16 17:06:04 2019 -0500

    gitlab-ci: Use G_SLICE=always-malloc in tests
    
    This allows to catch errors better, as per MALLOC_CHECK_'s definition
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/581

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a06f9ee47..a5b576ec2 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -35,6 +35,7 @@ test-mutter:
   variables:
     XDG_RUNTIME_DIR: "$CI_PROJECT_DIR/runtime-dir"
     GSETTINGS_SCHEMA_DIR: "$CI_PROJECT_DIR/build/data"
+    G_SLICE: "always-malloc"
     MALLOC_CHECK_: "3"
     NO_AT_BRIDGE: "1"
     MALLOC_PERTURB_: "123"