Remove unused never_type feature.

Author: nnethercote

compiler/rustc_incremental/src/lib.rs

@@ -5,7 +5,6 @@
 #![cfg_attr(not(bootstrap), doc(rust_logo))]
 #![cfg_attr(not(bootstrap), feature(rustdoc_internals))]
 #![cfg_attr(not(bootstrap), allow(internal_features))]
-#![feature(never_type)]
 #![recursion_limit = "256"]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]