New Defects reported by Coverity Scan for LibreOffice

[Caolán McNamara]

On Sun, 2018-05-27 at 22:28 +0000, scan-admin at coverity.com wrote:
> *** CID 1078573:  Null pointer dereferences  (FORWARD_NULL)
> /sw/source/core/docnode/swbaslnk.cxx

Since 7581730b2795a58d4fe6868e2f61572a91fde293 lcl_CallModify ends
up as...

bool bUpdate = false;
SwGrfNode* pSwGrfNode = nullptr;
if (m_pContentNode->IsGrfNode())
    ...
else if( m_pContentNode->IsOLENode() )
    bUpdate = true;

if (bUpdate)
    ...
    SetGrfFlySize(aGrfSz, pSwGrfNode, aOldSz)

so on the face of it, if its an ole node and not a graphic
SetGrfFlySize now derefs null pSwGrfNode.