no_std support for substrate trie (#2146)

* no_std trie compile in test_runtime (require to set nightly feature due
to the way hashbrown currently works).

* No nightly with hashmap_core.

* using crate elastic-array

* switch to publish trie crates

* fix default array decl

* bump impl_version for ci

* set all semver when possible wasm, and remove redundant code.

* Actually test use_trie function

* impl version +1

* Bump impl version

substrate/core/sr-std/with_std.rs

@@ -30,6 +30,7 @@ pub use std::ptr;
 pub use std::rc;
 pub use std::slice;
 pub use std::vec;
+pub use std::default;
 pub use std::result;
 
 pub mod collections {