coverity#1371215 Missing move assignment operator

Change-Id: Icfea2ad2ba98d7537cf1963ad3832ade192c5fd4

sw/source/filter/ww8/wrtww8.cxx

@@ -2763,7 +2763,7 @@ void MSWordExportBase::WriteText()
         }
 
         if (pNextNode != nullptr)
-            m_pCurPam->GetPoint()->nNode = SwNodeIndex(*pNextNode);
+            m_pCurPam->GetPoint()->nNode.Assign(*pNextNode);
         else
             ++m_pCurPam->GetPoint()->nNode;