Stablize the alloc module without changing stability of its contents.

src/test/compile-fail/lint-stability-fields.rs

@@ -18,6 +18,11 @@
 mod cross_crate {
     extern crate lint_stability_fields;
 
+    mod reexport {
+        #[stable(feature = "rust1", since = "1.0.0")]
+        pub use super::lint_stability_fields::*;
+    }
+
     use self::lint_stability_fields::*;
 
     pub fn foo() {
@@ -73,6 +78,8 @@ mod cross_crate {
             // the patterns are all fine:
             { .. } = x;
 
+        // Unstable items are still unstable even when used through a stable "pub use".
+        let x = reexport::Unstable2(1, 2, 3); //~ ERROR use of unstable
 
         let x = Unstable2(1, 2, 3); //~ ERROR use of unstable