Use generic NonZero internally.

compiler/rustc_middle/src/ty/mod.rs

@@ -61,7 +61,7 @@ use std::fmt::Debug;
 use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem;
-use std::num::NonZeroUsize;
+use std::num::NonZero;
 use std::ops::ControlFlow;
 use std::ptr::NonNull;
 use std::{fmt, str};
@@ -618,7 +618,7 @@ impl<'tcx> Term<'tcx> {
     #[inline]
     pub fn unpack(self) -> TermKind<'tcx> {
         let ptr = unsafe {
-            self.ptr.map_addr(|addr| NonZeroUsize::new_unchecked(addr.get() & !TAG_MASK))
+            self.ptr.map_addr(|addr| NonZero::<usize>::new_unchecked(addr.get() & !TAG_MASK))
         };
         // SAFETY: use of `Interned::new_unchecked` here is ok because these
         // pointers were originally created from `Interned` types in `pack()`,