Auto merge of #43406 - canndrew:never-impl-clone, r=alexcrichton

Add missing `!: Clone` impl

Fixes #43296

(untested because I'm having computer troubles, but a one-liner can't break anything right?)

Author: bors

src/libcore/clone.rs

@@ -165,6 +165,7 @@ clone_impl! { u128 }
 clone_impl! { f32 }
 clone_impl! { f64 }
 
+clone_impl! { ! }
 clone_impl! { () }
 clone_impl! { bool }
 clone_impl! { char }