remove extra size in favour of vector size and don't resize
and memcpy data, just use vector::insert

Change-Id: I8efb91a8c11fbd862c0458042554cf7e94b813cd
Reviewed-on: https://gerrit.libreoffice.org/34891Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>