fix rustdoc tests

Author: fee1-dead

core/src/marker.rs

@@ -960,7 +960,7 @@ marker_impls! {
 #[lang = "destruct"]
 #[rustc_on_unimplemented(message = "can't drop `{Self}`", append_const_msg)]
 #[rustc_deny_explicit_impl(implement_via_object = false)]
-// FIXME(effects) #[const_trait]
+#[const_trait]
 pub trait Destruct {}
 
 /// A marker for tuple types.