Revert "core: update DAO soft-fork number, clean up the code"

This reverts commit ba784bdf36.

core/state/statedb.go

@@ -51,6 +51,8 @@ type StateDB struct {
 	txIndex      int
 	logs         map[common.Hash]vm.Logs
 	logSize      uint
+
+	reducedDao bool
 }
 
 // Create a new state from a given trie