core/state, core/vm: reworked storage get / set to use common.Hash

common/types.go

@@ -62,6 +62,10 @@ func (h Hash) Generate(rand *rand.Rand, size int) reflect.Value {
 	return reflect.ValueOf(h)
 }
 
+func EmptyHash(h Hash) bool {
+	return h == Hash{}
+}
+
 /////////// Address
 func BytesToAddress(b []byte) Address {
 	var a Address