[gnome-builder] build: add gnome-common to flatpak for libpeas

[Christian Hergert <chergert src gnome org>]

commit 3dfc0f5b05358dd5dec044a293265acf8de68487
Author: Christian Hergert <chergert redhat com>
Date:   Thu Aug 1 10:26:47 2019 -0700

    build: add gnome-common to flatpak for libpeas

 build-aux/flatpak/org.gnome.Builder.json | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/build-aux/flatpak/org.gnome.Builder.json b/build-aux/flatpak/org.gnome.Builder.json
index 466c192a0..57da6f5b1 100644
--- a/build-aux/flatpak/org.gnome.Builder.json
+++ b/build-aux/flatpak/org.gnome.Builder.json
@@ -244,6 +244,16 @@
                 }
             ]
         },
+        {
+            "name" : "gnome-common",
+            "cleanup" : [ "*" ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/gnome-common.git";
+                }
+            ]
+        },
         {
             "name" : "libpeas",
             "cleanup" : [