Refactors references to MemoryLruCache in ethcore (#6693)

ethcore/evm/src/interpreter/shared_cache.rs

@@ -19,7 +19,7 @@ use hash::KECCAK_EMPTY;
 use heapsize::HeapSizeOf;
 use bigint::hash::H256;
 use parking_lot::Mutex;
-use util::cache::MemoryLruCache;
+use memory_cache::MemoryLruCache;
 use bit_set::BitSet;
 use super::super::instructions;
 

ethcore/evm/src/lib.rs

@@ -23,6 +23,7 @@ extern crate parking_lot;
 extern crate heapsize;
 extern crate vm;
 extern crate hash;
+extern crate memory_cache;
 
 #[macro_use]
 extern crate lazy_static;