LatinIME: Enable spellchecker for additional languages

We include more dictionaries than stock builds so let's
also enable spell checking for languages that use only
the supported unicode characters.

Change-Id: Iff9aea56edde10e47a754df39682f4f72c269756

LatinIME: Enable Greek spell checking

* We already ship a dictionary for Greek

Change-Id: I99ee7c98a88515c4c69b654210c10696135d7560