no need to initialise twice,
actually no need to explicit initialise unique_ptr to nullptr

Change-Id: Iff213722e22a0056d7e4c635e62437479c021f08
Reviewed-on: https://gerrit.libreoffice.org/33389Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>