Remove visual noise from hwpfilter

Change-Id: I57ea366a5ba585374773f53ca6cee99085fd846a
Reviewed-on: https://gerrit.libreoffice.org/8267
Tested-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>