Make Clone::clone a lang item · model-checking/verify-rust-std@8488ae6

Original file line number	Diff line number	Diff line change
`@@ -160,6 +160,9 @@ pub trait Clone: Sized {`
`160`	`160`	/// ```
`161`	`161`	`#[stable(feature = "rust1", since = "1.0.0")]`
`162`	`162`	`#[must_use = "cloning is often expensive and is not expected to have side effects"]`
	`163`	`+// Clone::clone is special because the compiler generates MIR to implement it for some types.`
	`164`	`+// See InstanceKind::CloneShim.`
	`165`	`+#[cfg_attr(not(bootstrap), lang = "clone_fn")]`
`163`	`166`	`fn clone(&self) -> Self;`
`164`	`167`
`165`	`168`	/// Performs copy-assignment from `source`.