Rust 2018 cleanup

programs/native/system/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/system/src/lib.rs

@@ -1,11 +1,8 @@
-#[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::system_instruction::SystemInstruction;
 use solana_sdk::system_program;