fdo#81272 Speed up break iterators

Change-Id: I7a45a61465f71a1cc6f583b9ffc68157d19e51fa
Reviewed-on: https://gerrit.libreoffice.org/11386
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>