wcscpy_s is buffer size, not string length, so size must also account
for a terminating NULL

Change-Id: Ie69692e47c142f3b733b093d0b87fa4bb03db7b4
(cherry picked from commit 2279f1f0)
Reviewed-on: https://gerrit.libreoffice.org/16653Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>