perf: buffer SipHasher128

Author: tgnottingham

compiler/rustc_data_structures/src/lib.rs

@@ -28,6 +28,7 @@
 #![feature(const_panic)]
 #![feature(min_const_generics)]
 #![feature(once_cell)]
+#![feature(maybe_uninit_uninit_array)]
 #![allow(rustc::default_hash_types)]
 
 #[macro_use]