ethcore/sync Make view macro only visible to test (#9316)

* remove needless macro import

* enable ethcore/macros in tests

ethcore/sync/src/lib.rs

@@ -26,7 +26,7 @@ extern crate ethcore_network_devp2p as devp2p;
 extern crate parity_bytes as bytes;
 extern crate ethcore_io as io;
 extern crate ethcore_transaction as transaction;
-#[macro_use]
+#[cfg_attr(test, macro_use)]
 extern crate ethcore;
 extern crate ethereum_types;
 extern crate env_logger;