Remove declaration of stable attributes

Author: alexcrichton

crates/coresimd/src/lib.rs

@@ -23,7 +23,6 @@
     core_intrinsics,
     crate_in_paths,
     no_core,
-    attr_literals,
     rustc_attrs,
     stdsimd,
     staged_api,
@@ -40,7 +39,6 @@
 #![cfg_attr(
     test,
     feature(
-        use_extern_macros,
         test,
         abi_vectorcall,
         untagged_unions

crates/stdsimd-test/src/lib.rs

@@ -4,7 +4,6 @@
 //! output once globally and then provides the `assert` function which makes
 //! assertions about the disassembly of a function.
 
-#![feature(use_extern_macros)]
 #![cfg_attr(
     feature = "cargo-clippy",
     allow(missing_docs_in_private_items, print_stdout)