[gtk/wip/chergert/quartz4u] build: add atk subproject

[Christian Hergert <chergert src gnome org>]

commit bc3b5753e352d89906bc075267d7780f0a6bf0e5
Author: Christian Hergert <chergert redhat com>
Date:   Tue Apr 28 12:48:57 2020 -0700

    build: add atk subproject

 meson.build | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 75af273d9d..1989647427 100644
--- a/meson.build
+++ b/meson.build
@@ -374,7 +374,8 @@ pixbuf_dep     = dependency('gdk-pixbuf-2.0', version: gdk_pixbuf_req,
 epoxy_dep      = dependency('epoxy', version: epoxy_req,
                             fallback: ['libepoxy', 'libepoxy_dep'],
                             static: false)
-atk_dep        = dependency('atk', version: atk_req)
+atk_dep        = dependency('atk', version: atk_req,
+                            fallback : ['atk', 'libatk_dep'])
 harfbuzz_dep   = dependency('harfbuzz', version: '>= 0.9', required: false)
 xkbdep         = dependency('xkbcommon', version: xkbcommon_req, required: wayland_enabled)
 graphene_dep   = dependency('graphene-gobject-1.0', version: graphene_req,