rhbz#1031989 Accept --pt in addition to deprecated -pt

Change-Id: I3593b3fc7e0ad405612216fb07e8632050b75cee
(cherry picked from commit 5cb10c4c99e46c97984e4e1c1bca5915f83f0a1d)
Reviewed-on: https://gerrit.libreoffice.org/6723
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>