Change orphan list semantics a bit

benchmark/addressbook.capnp.orphan.py

@@ -11,7 +11,7 @@ print = lambda *x: x
 def writeAddressBook(fd):
     message = capnp.MallocMessageBuilder()
     addressBook = message.initRoot(addressbook.AddressBook)
-    people = addressBook.init('people', 0)
+    people = addressBook.initResizableList('people')
 
     alice = people.add()
     alice.id = 123
@@ -31,6 +31,8 @@ def writeAddressBook(fd):
     bobPhones[1].number = "555-7654"
     bobPhones[1].type = 'work'
 
+    people.finish()
+
     capnp.writePackedMessageToFd(fd, message)