[gtk/macos-ci] ci: Add a macos build

[Matthias Clasen <matthiasc src gnome org>]

commit ec80c9c230b6db48ba534cb83bea077629b270ea
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Jan 2 22:34:52 2021 -0500

    ci: Add a macos build

 .gitlab-ci.yml | 11 +++++++++++
 1 file changed, 11 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 18565b2913..4bc1af4940 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -144,6 +144,17 @@ msys2-mingw64:
     MSYSTEM: "MINGW64"
     CHERE_INVOKING: "yes"
 
+macos:
+  stage: build
+  allow_failure: true
+  tags:
+    - macos
+  script:
+    - meson subprojects update
+    - meson ${COMMON_MESON_FLAGS} ${EXTRA_MESON_FLAGS} ${BACKEND_FLAGS} ${FEATURE_FLAGS}
+            _build
+    - ninja -C _build
+
 .flatpak-defaults:
   image: $FLATPAK_IMAGE
   stage: flatpak