Silence deprecation warnings in stdarch

Author: Mark-Simulacrum

library/core/src/lib.rs

@@ -412,7 +412,8 @@ pub mod primitive;
     dead_code,
     unused_imports,
     unsafe_op_in_unsafe_fn,
-    ambiguous_glob_reexports
+    ambiguous_glob_reexports,
+    deprecated_in_future
 )]
 #[allow(rustdoc::bare_urls)]
 // FIXME: This annotation should be moved into rust-lang/stdarch after clashing_extern_declarations is