coverity#708547 Uninitialized scalar field

Change-Id: Ib74b633355cc35d02a2a3847d2c98f2d52ca4a70

tools/source/generic/poly.cxx

@@ -1120,6 +1120,7 @@ public:
                             mnLow( nLow ),
                             mnHigh( nHigh ),
                             mnEdge( nEdge ),
+                            mnLastOutside( 0 ),
                             mbFirst( true )
                         {
                         }