Rollup merge of rust-lang#75855 - jyn514:no-cfg-doc, r=ollie27

Use allow(unused_imports) instead of cfg(doc) for imports used only for intra-doc links

This prevents links from breaking when items are re-exported in a
different crate and the original isn't being documented.

Spotted in rust-lang#75832 (comment) (thanks ollie!)

r? @ollie27

Author: JohnTitor

library/core/src/intrinsics.rs

@@ -58,7 +58,7 @@ use crate::marker::DiscriminantKind;
 use crate::mem;
 
 // These imports are used for simplifying intra-doc links
-#[cfg(doc)]
+#[allow(unused_imports)]
 use crate::sync::atomic::{self, AtomicBool, AtomicI32, AtomicIsize, AtomicU32, Ordering};
 
 #[stable(feature = "drop_in_place", since = "1.8.0")]