Fix broken links on std::boxed doc page

Author: ollie27

src/liballoc/boxed.rs

@@ -63,6 +63,8 @@
 //!
 //! [dereferencing]: ../../std/ops/trait.Deref.html
 //! [`Box`]: struct.Box.html
+//! [`Global`]: ../alloc/struct.Global.html
+//! [`Layout`]: ../alloc/struct.Layout.html
 
 #![stable(feature = "rust1", since = "1.0.0")]
 

src/liballoc/lib.rs

@@ -65,7 +65,7 @@
 #![allow(explicit_outlives_requirements)]
 
 #![warn(deprecated_in_future)]
-#![warn(intra_doc_link_resolution_failure)]
+#![deny(intra_doc_link_resolution_failure)]
 #![warn(missing_debug_implementations)]
 
 #![cfg_attr(not(test), feature(generator_trait))]

src/libcore/lib.rs

@@ -60,7 +60,7 @@
 
 #![warn(deprecated_in_future)]
 #![warn(missing_docs)]
-#![warn(intra_doc_link_resolution_failure)]
+#![deny(intra_doc_link_resolution_failure)]
 #![warn(missing_debug_implementations)]
 
 #![feature(allow_internal_unstable)]