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

This reverts commit ba784bdf36.

core/vm/runtime/runtime.go

@@ -35,17 +35,18 @@ func (ruleSet) IsHomestead(*big.Int) bool { return true }
 // Config is a basic type specifying certain configuration flags for running
 // the EVM.
 type Config struct {
-	RuleSet     vm.RuleSet
-	Difficulty  *big.Int
-	Origin      common.Address
-	Coinbase    common.Address
-	BlockNumber *big.Int
-	Time        *big.Int
-	GasLimit    *big.Int
-	GasPrice    *big.Int
-	Value       *big.Int
-	DisableJit  bool // "disable" so it's enabled by default
-	Debug       bool
+	RuleSet       vm.RuleSet
+	Difficulty    *big.Int
+	Origin        common.Address
+	Coinbase      common.Address
+	BlockNumber   *big.Int
+	Time          *big.Int
+	GasLimit      *big.Int
+	GasPrice      *big.Int
+	Value         *big.Int
+	DisableJit    bool // "disable" so it's enabled by default
+	Debug         bool
+	illegalHashes []common.Hash
 
 	State     *state.StateDB
 	GetHashFn func(n uint64) common.Hash