ofz#1220 sanitize nTyp to legal values

Change-Id: Iad71c4f79dbe03e2e325453eb0506a2d92d67c2d
Reviewed-on: https://gerrit.libreoffice.org/36891Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sw/source/filter/ww8/ww8graf.cxx

@@ -1295,7 +1295,7 @@ SdrObject* SwWW8ImplReader::ReadCaptionBox(WW8_DPHEAD* pHd, SfxAllItemSet &rSet)
     else                                                // no -> take lines
         SetStdAttr( rSet, aCallB.dpPolyLine.aLnt, aCallB.dptxbx.aShd );
     SetFill( rSet, aCallB.dptxbx.aFill );
-    rSet.Put( SdrCaptionTypeItem( aCaptA[nTyp] ) );
+    rSet.Put(SdrCaptionTypeItem(aCaptA[nTyp % SAL_N_ELEMENTS(aCaptA)]));
 
     return pObj;
 }