* lisp/textmodes/ispell.el: Fix finding dictionaries for Enchant.

* lisp/textmodes/ispell.el: Fix finding dictionaries for Enchant.

(ispell-find-enchant-dictionaries):

I originally copied this code from the equivalent code for
Aspell. Unfortunately it was wrong for the case of Enchant: it should
find only dictionaries that Enchant knows about, and not merge in
`ispell-dictionary-base-alist' or add a default element, as these
are dealt with in `ispell-set-spellchecker-params'.

This caused a bug where the correct `-d' argument would not be added
to the invocation of enchant, leading to the process not being
correctly started.