Don't include appdata-rng-init.el in the distribution tarball

File ```/usr/share/emacs/site-lisp/site-start.d/appdata-rng-init.el``` contains the following when installed from the Fedora RPM:

```
       (add-to-list 'rng-schema-locating-files
                    "/home/hughsie/.root/share/appdata/schema/schema-locating-rules.xml" t))
```

This is because it's getting included in the distribution tarball and then isn't later rebuilt.