Fix netlist changes netnames randomly when netnames come from power pins invisible connected together but having different names.

eeschema/netlist.cpp

@@ -426,7 +426,7 @@ static bool evalLabelsPriority( const NETLIST_OBJECT* aLabel1,
     // and for a given path length, by alphabetic order
 
     if( aLabel1->m_Type == NET_PINLABEL || aLabel1->m_Type == NET_GLOBLABEL )
-        return aLabel1->m_Label.Cmp( aLabel2->m_Label );
+        return aLabel1->m_Label.Cmp( aLabel2->m_Label ) < 0;
 
     // not global: names are prefixed by their sheetpath
     // use name defined in higher hierarchical sheet