stabilize naked_functions

Author: folkertdev

compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs

@@ -1,13 +1,4 @@
-#![feature(
-    no_core,
-    lang_items,
-    never_type,
-    linkage,
-    extern_types,
-    naked_functions,
-    thread_local,
-    repr_simd
-)]
+#![feature(no_core, lang_items, never_type, linkage, extern_types, thread_local, repr_simd)]
 #![no_core]
 #![allow(dead_code, non_camel_case_types, internal_features)]
 

compiler/rustc_error_codes/src/error_codes/E0787.md

@@ -3,8 +3,6 @@ An unsupported naked function definition.
 Erroneous code example:
 
 ```compile_fail,E0787
-#![feature(naked_functions)]
-
 #[naked]
 pub extern "C" fn f() -> u32 {
     42