gitlab-ci: Use runtime dir owned only by current user

https://gitlab.gnome.org/GNOME/mutter/merge_requests/408

.gitlab-ci.yml

@@ -24,8 +24,9 @@ test-mutter:
       - build
   script:
     - glib-compile-schemas $PWD/build/data
+    - mkdir -m 700 $PWD/runtime-dir
     - >
-      env XDG_RUNTIME_DIR=/tmp
+      env XDG_RUNTIME_DIR=$PWD/runtime-dir
       GSETTINGS_SCHEMA_DIR=$PWD/build/data
       dbus-run-session -- xvfb-run -s '+iglx -noreset'
       meson test -C build --no-rebuild -t 10 --verbose --no-stdsplit --wrap catchsegv