- <GfxLink> instance - also for the reading of preview picture data

in order to avoid trouble on save in case that the preview data equals the
picture data

(cherry picked from commit d6af1b60)

Conflicts:
	svx/source/svdraw/svdograf.cxx

Change-Id: Ifecb07b4d5d33d593502fccd6f21644893027d2d