Add lockouts to vote program (#2944)

* Add lockouts to vote program

* Rename MAX_VOTE_HISTORY TO MAX_LOCKOUT_HISTORY, change process_vote() to only pop votes after MAX_LOCKOUT_HISTORY + 1 votes have arrived

* Correctly calculate serialized size of an Option, rename root_block to root_slot

runtime/src/bank.rs

@@ -223,7 +223,9 @@ impl Bank {
             genesis_block.bootstrap_leader_id,
             genesis_block.bootstrap_leader_id,
         );
-        vote_state.votes.push_back(vote_program::Vote::new(0));
+        vote_state
+            .votes
+            .push_back(vote_program::Lockout::new(&vote_program::Vote::new(0)));
         vote_state
             .serialize(&mut bootstrap_leader_vote_account.userdata)
             .unwrap();