forcepoint #29 detect illegal self series add

Change-Id: I3bba0f942780c54951a3a810c05cc3b56ca18a5e
Reviewed-on: https://gerrit.libreoffice.org/51862Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
(cherry picked from commit a471620a)

sc/source/filter/excel/xichart.cxx

@@ -1867,6 +1867,11 @@ void XclImpChSeries::SetDataLabel( const XclImpChTextRef& xLabel )
 void XclImpChSeries::AddChildSeries( const XclImpChSeries& rSeries )
 {
     OSL_ENSURE( !HasParentSeries(), "XclImpChSeries::AddChildSeries - not allowed for child series" );
+    if (&rSeries == this)
+    {
+        SAL_WARN("sc.filter", "self add attempt");
+        return;
+    }
 
     /*  In Excel, trend lines and error bars are stored as own series. In Calc,
         these are properties of the parent series. This function adds the