Rollup merge of #21591 - GuillaumeGomez:hash, r=alexcrichton

Fixes #21547 issue.

src/libcore/nonzero.rs

@@ -31,7 +31,7 @@ unsafe impl Zeroable for u64 {}
 /// A wrapper type for raw pointers and integers that will never be
 /// NULL or 0 that might allow certain optimizations.
 #[lang="non_zero"]
-#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Show)]
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Show, Hash)]
 #[unstable]
 pub struct NonZero<T: Zeroable>(T);