(cherry picked from commit e3b59350ddceb158d01dedfe368bb600a9b37ea8)

Also includes...
graphic: move access to cxx for PDFData and VectorGraphicData

We need strict control when PDFData and VectorGraphicData is
accessed and changed, so create access methods for PDFData and
move the access methods to cxx (for VectorGraphicData).

Reviewed-on: https://gerrit.libreoffice.org/52395Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
(cherry picked from commit 18caee07)

Change-Id: I39324a807a4db559bad5501b5913e62a0aeabf01
8146aa4e206788afff71142e1877fd7a885f4652