Fix nightly flatpak EDS build error

Manually build intltool until eds gets ported to use it.

Patch taken from 2b3023232f

See GNOME/evolution-data-server#77

org.gnome.Geary.json

@@ -144,6 +144,17 @@
                 }
             ]
         },
+        {
+            "name": "intltool",
+            "cleanup": [ "*" ],
+            "sources": [
+                {
+                    "type": "archive",
+                    "url": "https://launchpad.net/intltool/trunk/0.51.0/+download/intltool-0.51.0.tar.gz",
+                    "sha256": "67c74d94196b153b774ab9f89b2fa6c6ba79352407037c8c14d5aeb334e959cd"
+                }
+            ]
+        },
         {
             "name": "evolution-data-server",
             "cleanup": [