Languages don't always have a country; if there is no "-" separating
language and country in the ooLocale registry value, use the entire
value as the language.

Initial finding by Damjan Jovanovic.
However, LibreOffice knows BCP47 language tags so that needs a different
approach.

(cherry picked from commit d61ab2b5)

Change-Id: I69331951372bda1c1cec80cfd10d5839d8f4b823
Reviewed-on: https://gerrit.libreoffice.org/30154Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>