Revert "rm extra reference to linked_hash_*"

This reverts commit dfce1e0.

Author: robinbernon

src/lib.rs

@@ -1,5 +1,5 @@
-mod linked_hash_map;
-mod linked_hash_set;
+pub mod linked_hash_map;
+pub mod linked_hash_set;
 pub mod lru_cache;
 #[cfg(feature = "serde_impl")]
 pub mod serde;