Bump stdarch submodule

library/core/src/lib.rs

@@ -418,6 +418,7 @@ pub mod primitive;
 // FIXME: This annotation should be moved into rust-lang/stdarch after clashing_extern_declarations is
 // merged. It currently cannot because bootstrap fails as the lint hasn't been defined yet.
 #[allow(clashing_extern_declarations)]
+#[cfg_attr(bootstrap, allow(deprecated_in_future))]
 #[unstable(feature = "stdsimd", issue = "48556")]
 mod core_arch;