Reformat imports to a consistent style for imports

rustfmt.toml configuration:
        imports_granularity = "One"
         group_imports = "One"

sdk/benches/serialize_instructions.rs

@@ -1,12 +1,16 @@
 #![feature(test)]
 
 extern crate test;
-use bincode::{deserialize, serialize};
-use solana_sdk::instruction::{AccountMeta, Instruction};
-use solana_sdk::message::Message;
-use solana_sdk::pubkey;
-use solana_sdk::sysvar::instructions;
-use test::Bencher;
+use {
+    bincode::{deserialize, serialize},
+    solana_sdk::{
+        instruction::{AccountMeta, Instruction},
+        message::Message,
+        pubkey,
+        sysvar::instructions,
+    },
+    test::Bencher,
+};
 
 fn make_instructions() -> Vec<Instruction> {
     let meta = AccountMeta::new(pubkey::new_rand(), false);

sdk/benches/short_vec.rs

@@ -1,9 +1,7 @@
 #![feature(test)]
 
 extern crate test;
-use bincode::deserialize;
-use solana_sdk::short_vec::ShortVec;
-use test::Bencher;
+use {bincode::deserialize, solana_sdk::short_vec::ShortVec, test::Bencher};
 
 // Return a ShortVec with 127 bytes
 fn create_encoded_short_vec() -> Vec<u8> {

sdk/benches/slot_hashes.rs

@@ -1,12 +1,14 @@
 #![feature(test)]
 
 extern crate test;
-use solana_sdk::{
-    account::{create_account_for_test, from_account},
-    hash::Hash,
-    slot_hashes::{Slot, SlotHashes, MAX_ENTRIES},
+use {
+    solana_sdk::{
+        account::{create_account_for_test, from_account},
+        hash::Hash,
+        slot_hashes::{Slot, SlotHashes, MAX_ENTRIES},
+    },
+    test::Bencher,
 };
-use test::Bencher;
 
 #[bench]
 fn bench_to_from_account(b: &mut Bencher) {

sdk/benches/slot_history.rs

@@ -1,11 +1,13 @@
 #![feature(test)]
 
 extern crate test;
-use solana_sdk::{
-    account::{create_account_for_test, from_account},
-    slot_history::SlotHistory,
+use {
+    solana_sdk::{
+        account::{create_account_for_test, from_account},
+        slot_history::SlotHistory,
+    },
+    test::Bencher,
 };
-use test::Bencher;
 
 #[bench]
 fn bench_to_from_account(b: &mut Bencher) {