Remove "benches" feature

Now benches just live with the rest of the code in the default feature.

Cargo.toml

@@ -36,6 +36,3 @@ ring = { git = "https://github.com/paritytech/ring" }
 [[bin]]
 path = "lighthouse/main.rs"
 name = "lighthouse"
-
-[features]
-benches = []

lighthouse/state/block/validation/benches.rs

@@ -66,6 +66,7 @@ fn bench_block_validation_scenario<F>(
 }
 
 #[bench]
+#[ignore]
 fn bench_block_validation_10m_eth(b: &mut Bencher) {
     let total_validators: usize = 10_000_000 / 32;
     let cycle_length: u8 = 64;
@@ -105,6 +106,7 @@ fn bench_block_validation_10m_eth(b: &mut Bencher) {
 }
 
 #[bench]
+#[ignore]
 fn bench_block_validation_100m_eth(b: &mut Bencher) {
     let total_validators: usize = 100_000_000 / 32;
     let cycle_length: u8 = 64;