ci: reduce nolibdecor build to xwayland only

libdecor is only relevant for Xwayland, so no need to build all the
other DDX'es for this build test. Remvoving some unncessary load from
CI machines by disabling all DDX'es but Xwayland here.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1676>

.gitlab-ci.yml

@@ -180,11 +180,11 @@ meson-noglamor:
         MESON_EXTRA_ARGS: >
           -Dglamor=false
 
-meson-nolibdecor:
+xwayland-nolibdecor:
     extends: meson
     variables:
         MESON_EXTRA_ARGS: >
-          -Dlibdecor=false
+          -Dlibdecor=false -Dxorg=false -Dxephyr=false -Dxvfb=false -Dxnest=false
 
 mingw-cross-build:
     extends: .common-build-and-test