core/state: make TestSnapshotRandom work again (#3816)

In `touch` operation, only `touched` filed has been changed. Therefore
in the related undo function, only `touched` field should be reverted.
In addition, whether remove this obj from dirty map should depend on
prevDirty flag.

core/state/state_object.go

@@ -137,8 +137,9 @@ func (self *stateObject) markSuicided() {
 
 func (c *stateObject) touch() {
 	c.db.journal = append(c.db.journal, touchChange{
-		account: &c.address,
-		prev:    c.touched,
+		account:   &c.address,
+		prev:      c.touched,
+		prevDirty: c.onDirty == nil,
 	})
 	if c.onDirty != nil {
 		c.onDirty(c.Address())