We internally use the string "zz" to mean no locale, but
the user dictionary service does not understand that and
words added with this locale pitifully end being added to
a "zz" user dictionary, which makes no sense to the user.
This change fixes things so that words added when the
keyboard is in a "no locale" layout, the words are added
to the global, all-locales user dictionary.

Bug: 6645306
Change-Id: Iec3cdd1fe3d5bc43427a43ef9ae9bf89e12be1f2