Split out substrate-primitives from polkadot-primitives.

Bottom half minus tests builds.

substrate/codec/Cargo.toml

@@ -5,7 +5,8 @@ version = "0.1.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 
 [dependencies]
+substrate-runtime-std = { path = "../runtime-std", default_features = false }
 
 [features]
-std = []
 default = ["std"]
+std = ["substrate-runtime-std/std"]

substrate/codec/src/lib.rs

@@ -30,6 +30,7 @@ pub use self::slicable::{Slicable, NonTrivialSlicable};
 pub use self::joiner::Joiner;
 pub use self::keyedvec::KeyedVec;
 
+// TODO: move these into runtime-std and `extern crate runtime_std as std;`
 #[cfg(not(feature = "std"))]
 mod std {
 	extern crate alloc;