sw: tweak CrossRefBookmark hack to re-sort if applied

Change-Id: I8ea68819a87abecb2a6561fbd5b695902dd4af63
(cherry picked from commit 4a273473)

sw/source/core/doc/docbm.cxx

@@ -636,6 +636,7 @@ namespace sw { namespace mark
                 {
                     // ensure that cross ref bookmark always starts at 0
                     aNewPosRel.nContent = 0; // HACK for WW8 import
+                    isSortingNeeded = true; // and sort them to be safe...
                 }
                 aNewPosRel.nContent += pMark->GetMarkPos().nContent.GetIndex();
                 pMark->SetMarkPos(aNewPosRel);