Use serde derive feature. (#2351)

* core/primitives

* sr-primitives

* sr-primitives

* srml-treasury

* substrate-executor

* substrate-keystore

* network-libp2p

* substrate-service

* srml-system

* substrate-rpc

* sr-version

* substrate-telemetry

* substrate-test-runtime

* substrate-transaction-pool

* node-template-runtime

* node-primitives

* srml-consensus

* srml-contract

* srml-democracy

* srml-finality-tracker

* srml-grandpa

* srml-metadata

* srml-support

* Clean

* Update locks

substrate/srml/system/Cargo.toml

@@ -6,8 +6,7 @@ edition = "2018"
 
 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", optional = true }
-serde_derive = { version = "1.0", optional = true }
+serde = { version = "1.0", optional = true, features = ["derive"] }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.5", default-features = false, features = ["derive"] }
 substrate-primitives = { path = "../../core/primitives", default-features = false }
@@ -23,7 +22,6 @@ criterion = "0.2"
 default = ["std"]
 std = [
 	"serde",
-	"serde_derive",
 	"safe-mix/std",
 	"parity-codec/std",
 	"substrate-primitives/std",
@@ -35,4 +33,4 @@ std = [
 
 [[bench]]
 name = "bench"
-harness = false
+harness = false

substrate/srml/system/src/lib.rs

@@ -72,7 +72,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 #[cfg(feature = "std")]
-use serde_derive::Serialize;
+use serde::Serialize;
 use rstd::prelude::*;
 #[cfg(any(feature = "std", test))]
 use rstd::map;