bnc#822347: if number type is not set, skip numbering

If numbering is detected then (level is > 0) and the number type
is not set, the defult bullet symbol is written. This is not
correct as the default should be SVX_NUM_NUMBER_NONE which should
skip numbering or set it to none. With this change the numbering
is skipped (as in MSO).

Change-Id: I8d08a6325509c7bd6f96f64c8d29e5f3045458ca

oox/source/export/drawingml.cxx

@@ -1560,6 +1560,9 @@ void DrawingML::WriteParagraphNumbering( Reference< XPropertySet > rXPropSet, sa
         }
     }
 
+    if (nNumberingType == SVX_NUM_NUMBER_NONE)
+        return;
+
     if( !aGraphicURL.isEmpty() )
     {
         OUString sRelId = WriteImage( aGraphicURL );