Additional externs for ecdsa recovery and keccak (#1583)

* Additional externs for ecdsa recovery and keccak

* Update core/executor/src/wasm_executor.rs

Co-Authored-By: gavofyork <github@gavwood.com>

* Update core/executor/src/wasm_executor.rs

Co-Authored-By: gavofyork <github@gavwood.com>

* Fix grumble

* Grumble.

substrate/core/sr-io/src/lib.rs

@@ -25,6 +25,12 @@
 #![cfg_attr(feature = "std", doc = "Substrate runtime standard library as compiled when linked with Rust's standard library.")]
 #![cfg_attr(not(feature = "std"), doc = "Substrate's runtime standard library as compiled without Rust's standard library.")]
 
+pub enum EcdsaVerifyError {
+	BadRS,
+	BadV,
+	BadSignature,
+}
+
 #[cfg(feature = "std")]
 include!("../with_std.rs");