just use a std::vector here, these are small objects, no need to
allocate them separately

Change-Id: Ie9f8df88eb7c291e2c99177d0f5e4bfc1c7ab542
Reviewed-on: https://gerrit.libreoffice.org/51415Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>