fdo#81272 Speed up break iterators

Change-Id: Idcd7de83ff7e551b350db0bf80e2ac78baa67686
Reviewed-on: https://gerrit.libreoffice.org/11374
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>