Merge ref '28d0a4a205f9' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: 28d0a4a
Filtered ref: 310e49750b70768361f78966c10be9716a300784
Upstream diff: 235a4c0...28d0a4a

This merge was created using https://github.com/rust-lang/josh-sync.

src/tools/miri/src/shims/native_lib/mod.rs

@@ -6,6 +6,7 @@ use std::sync::atomic::AtomicBool;
 use libffi::low::CodePtr;
 use libffi::middle::Type as FfiType;
 use rustc_abi::{HasDataLayout, Size};
+use rustc_data_structures::either;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_middle::ty::{self, IntTy, Ty, UintTy};
 use rustc_span::Symbol;