mozc support in the default ISO

[Jeremy Bicha]

gnome-desktop 3.27.1 was released today and changed GNOME's default
Japanese input method from ibus-anthy to ibus-kkc.

https://git.gnome.org/browse/gnome-desktop/commit/?id=9c1aea9d

The GNOME bug is interesting since it originally requested switching
to ibus-mozc (Ubuntu's current default) but eventually they preferred
to use kkc because it has GTK+ tools:
https://bugzilla.gnome.org/787664

I guess we need to patch gnome-desktop if Ubuntu decides to use
different default input methods for certain languages.

https://git.gnome.org/browse/gnome-desktop/tree/libgnome-desktop/default-input-sources.h

Thanks,
Jeremy Bicha