fdo#73660: sw: fix Find of words containing soft-hyphen

Soft hyphen was not detected if there is no hint (-1).

(regression from ebeff3f074dd94dce4ce6cc55abd0495103684bd)

Change-Id: I09108796a32429a01eff93f797a6de521ab1d08a
(cherry picked from commit 156a0235bd8ff06840cecad1e70a57ffc5b8e7e1)
Reviewed-on: https://gerrit.libreoffice.org/7511
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>