Port core util lib to support no_std

src/ext.rs

@@ -1,3 +1,7 @@
+use std::string::String;
+use std::vec::Vec;
+use std::borrow::ToOwned;
+
 use parity_wasm::{elements, builder};
 use optimizer::{import_section, export_section};
 use byteorder::{LittleEndian, ByteOrder};
@@ -200,4 +204,4 @@ pub fn externalize(
 
 	module
 
-}
+}