Update code with new lint names

src/libcore/lib.rs

@@ -60,7 +60,7 @@
 #![allow(unknown_features)]
 #![feature(globs, intrinsics, lang_items, macro_rules, phase)]
 #![feature(simd, unsafe_destructor, slicing_syntax)]
-#![deny(missing_doc)]
+#![deny(missing_docs)]
 
 mod macros;