Rust 2018 cleanup

programs/native/vote/Cargo.toml

@@ -6,6 +6,7 @@ authors = ["Solana Maintainers <maintainers@solana.com>"]
 repository = "https://github.com/solana-labs/solana"
 license = "Apache-2.0"
 homepage = "https://solana.com/"
+edition = "2018"
 
 [dependencies]
 bincode = "1.0.0"

programs/native/vote/src/lib.rs

@@ -1,14 +1,11 @@
 //! Vote program
 //! Receive and processes votes from validators
 
-#[macro_use]
-extern crate log;
-#[macro_use]
-extern crate solana_sdk;
-
+use log::*;
 use solana_sdk::account::KeyedAccount;
 use solana_sdk::native_program::ProgramError;
 use solana_sdk::pubkey::Pubkey;
+use solana_sdk::solana_entrypoint;
 use solana_sdk::vote_program::*;
 use std::collections::VecDeque;
 
@@ -39,7 +36,7 @@ fn entrypoint(
 
             // TODO: a single validator could register multiple "vote accounts"
             // which would clutter the "accounts" structure. See github issue 1654.
-            let mut vote_state = VoteProgram {
+            let vote_state = VoteProgram {
                 votes: VecDeque::new(),
                 node_id: *keyed_accounts[0].signer_key().unwrap(),
             };