Revert #2172, pretty much. (#2387)

* Revert #2172, pretty much.

* Tidy up whitespace.

[ci:skip]

* Force CI.

ethash/src/compute.rs

@@ -202,6 +202,9 @@ impl SeedHashCompute {
 	}
 }
 
+pub fn slow_get_seedhash(block_number: u64) -> H256 {
+	SeedHashCompute::resume_compute_seedhash([0u8; 32], 0, block_number / ETHASH_EPOCH_LENGTH)
+}
 
 #[inline]
 fn fnv_hash(x: u32, y: u32) -> u32 {

ethash/src/lib.rs

@@ -26,7 +26,7 @@ mod compute;
 
 use std::mem;
 use compute::Light;
-pub use compute::{ETHASH_EPOCH_LENGTH, H256, ProofOfWork, SeedHashCompute, quick_get_difficulty};
+pub use compute::{ETHASH_EPOCH_LENGTH, H256, ProofOfWork, SeedHashCompute, quick_get_difficulty, slow_get_seedhash};
 
 use std::sync::Arc;
 use parking_lot::Mutex;