[gnome-control-center] flatpak: Add libhandy

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 459fb91a840bb878cd4a40f2ffd88b991026e100
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sat Sep 22 18:40:49 2018 +0200

    flatpak: Add libhandy
    
    This is needed as it is going to be used in the following commits.

 build-aux/flatpak/org.gnome.Settings.json | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
---
diff --git a/build-aux/flatpak/org.gnome.Settings.json b/build-aux/flatpak/org.gnome.Settings.json
index 767987de2..eaeedf5f4 100644
--- a/build-aux/flatpak/org.gnome.Settings.json
+++ b/build-aux/flatpak/org.gnome.Settings.json
@@ -506,6 +506,23 @@
                 }
             ]
         },
+        {
+            "name" : "libhandy",
+            "buildsystem" : "meson",
+            "config-opts" : [
+                "-Dexamples=false",
+                "-Dglade_catalog=false",
+                "-Dintrospection=false",
+                "-Dtests=false",
+                "-Dvapi=false"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://source.puri.sm/Librem5/libhandy.git";
+                }
+            ]
+        },
         {
             "name" : "gnome-control-center",
             "buildsystem" : "meson",