The "ignore diacritics" implementation is not only about CTL,
whatever its names suggest. It uses an ICU
"NFD; [:M:] Remove; NFC" transliteration that decomposes and
removes *any* diacritic.

Thus treat it as such and don't hide the checkbox if CTL is not
enabled, but more important preset the sensitive values, and
handle the UI vs implementation oddity correctly; UI "sensitive" /
code "include" means to *not* *ignore*, obtain the proper negated
value from the checkbox.

Unfortunately the setting is stored in the configuration, so an
update will still present the user with an unchecked
Diacritics-sensitive box s/he has to enable once.

The actual failure (diacritics always ignored) is a fallout from

    commit d4064927
    AuthorDate: Tue Oct 3 10:26:28 2017 -0800
    CommitDate: Thu Oct 26 17:24:26 2017 +0200

        tdf#111846 Find & Replace: Rename diacritics and kashida options

Change-Id: I65f2a23b66370fdfe2d170c17c7736a3b4177192