better fix for tdf#101563: Export to PDF creates huge PDF files

Change-Id: Idda6a5ac824090e620fc6577fc82d5c5f1234b7e
Reviewed-on: https://gerrit.libreoffice.org/33037Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Noel Grandin <noel.grandin@collabora.co.uk>

include/svtools/grfmgr.hxx

@@ -386,7 +386,7 @@ public:
     bool                    HasLink() const { return !maLink.isEmpty(); }
     void                    SetLink();
     void                    SetLink( const OUString& rLink );
-    OUString                GetLink() const { return maLink; }
+    const OUString&         GetLink() const { return maLink; }
 
     bool                    HasUserData() const { return !maUserData.isEmpty(); }
     void                    SetUserData();

svtools/source/graphic/grfmgr.cxx

@@ -647,8 +647,11 @@ void GraphicObject::SetGraphic( const Graphic& rGraphic, const GraphicObject* pC
 
 void GraphicObject::SetGraphic( const Graphic& rGraphic, const OUString& rLink )
 {
+    // in case we are called from a situation where rLink and maLink are the same thing,
+    // we need a copy because SetGraphic clears maLink
+    OUString sLinkCopy = rLink;
     SetGraphic( rGraphic );
-    maLink = rLink;
+    maLink = sLinkCopy;
 }
 
 Graphic GraphicObject::GetTransformedGraphic( const Size& rDestSize, const MapMode& rDestMap, const GraphicAttr& rAttr ) const