Fix compilation errors

ethcore/src/block.rs

@@ -303,7 +303,7 @@ impl<'x> OpenBlock<'x> {
                 warn!(
                     "Heavy ({} ms) transaction in block {:?}: {:?}",
                     took_ms,
-                    self.block.header().number(),
+                    self.block.header.number(),
                     hash
                 );
             }

ethcore/src/lib.rs

@@ -113,6 +113,8 @@ extern crate env_logger;
 extern crate ethcore_accounts as accounts;
 #[cfg(feature = "stratum")]
 extern crate ethcore_stratum;
+#[cfg(any(test, feature = "test-helpers"))]
+extern crate kvdb_memorydb;
 #[cfg(any(test, feature = "kvdb-rocksdb"))]
 extern crate kvdb_rocksdb;
 #[cfg(test)]