fdo#73565: Populate date members in a locale-safe way.

Change-Id: Id90b2829465fada690b0446d6d823e76e792c77b
(cherry picked from commit 2be2786879883badd6d0075e63965bacd312ed23)
Reviewed-on: https://gerrit.libreoffice.org/8139
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-on: https://gerrit.libreoffice.org/8140
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>