Refactors references to MemoryLruCache in ethcore (#6693)

ethcore/light/Cargo.toml

@@ -40,6 +40,7 @@ stats = { path = "../../util/stats" }
 hash = { path = "../../util/hash" }
 triehash = { path = "../../util/triehash" }
 kvdb = { path = "../../util/kvdb" }
+memory_cache = { path = "../../util/memory_cache" }
 
 [features]
 default = []

ethcore/light/src/cache.rs

@@ -29,7 +29,7 @@ use time::{SteadyTime, Duration};
 use heapsize::HeapSizeOf;
 use bigint::prelude::U256;
 use bigint::hash::H256;
-use util::cache::MemoryLruCache;
+use memory_cache::MemoryLruCache;
 
 /// Configuration for how much data to cache.
 #[derive(Debug, Clone, PartialEq, Eq)]

ethcore/light/src/lib.rs

@@ -92,6 +92,7 @@ extern crate vm;
 extern crate hash;
 extern crate triehash;
 extern crate kvdb;
+extern crate memory_cache;
 
 #[cfg(feature = "ipc")]
 extern crate ethcore_ipc as ipc;