Allow internal_features lint

src/lib.rs

@@ -1,6 +1,10 @@
 #![doc = include_str!("../README.md")]
 #![feature(c_unwind)]
 #![feature(naked_functions)]
+// lang_items is an internal feature. `internal_features` lint is added recently
+// so also allow unknown lints to prevent warning in older nightly versions.
+#![allow(unknown_lints)]
+#![allow(internal_features)]
 #![cfg_attr(
     any(feature = "personality", feature = "personality-dummy"),
     feature(lang_items)