intltool has been removed from the SDK and the release-team has
advised users to bundle it in their Flatpaks until the dependencies
get ported away from it. See
https://mail.gnome.org/archives/desktop-devel-list/2019-August/msg00000.html
This patch also ships with some polkit changes to make it suitable
for use within Flatpak. These changes were copied from gnome-builder.