Add slot_history for slashing (#7589)

* Add slot_history for slashing

* fixup

* fixup

sdk/benches/slot_history.rs

@@ -0,0 +1,15 @@
+#![feature(test)]
+
+extern crate test;
+use solana_sdk::{slot_history::SlotHistory, sysvar::Sysvar};
+use test::Bencher;
+
+#[bench]
+fn bench_to_from_account(b: &mut Bencher) {
+    let mut slot_history = SlotHistory::default();
+
+    b.iter(|| {
+        let account = slot_history.create_account(0);
+        slot_history = SlotHistory::from_account(&account).unwrap();
+    });
+}