for a graphic, if is already has one.

- needed correction for the fix made for issue #i114361#

(cherry picked from commit 23a4bd91)

Conflicts:
	sw/inc/ndgrf.hxx
	sw/source/core/graphic/ndgrf.cxx
	sw/source/filter/xml/xmltexte.cxx

Change-Id: Ia9771932ae5b380ccae9b0a3cbb79d41f5d9bdb8