Link test to compiler builtins and make unstable

This commit fixes a test which now needs to explicitly link to the
`compiler_builtins` crate as well as makes the `compiler_builtins` crate
unstable.

src/libcompiler_builtins/lib.rs

@@ -11,6 +11,9 @@
 #![cfg_attr(not(stage0), feature(compiler_builtins))]
 #![no_std]
 #![cfg_attr(not(stage0), compiler_builtins)]
-
+#![unstable(feature = "compiler_builtins_lib",
+            reason = "internal implementation detail of rustc right now",
+            issue = "0")]
 #![crate_name = "compiler_builtins"]
 #![crate_type = "rlib"]
+#![feature(staged_api)]

src/libstd/lib.rs

@@ -224,6 +224,7 @@
 #![feature(char_internals)]
 #![feature(collections)]
 #![feature(collections_bound)]
+#![feature(compiler_builtins_lib)]
 #![feature(const_fn)]
 #![feature(core_float)]
 #![feature(core_intrinsics)]

src/test/run-make/no-duplicate-libs/bar.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(lang_items, libc)]
+#![feature(lang_items, libc, compiler_builtins_lib)]
 #![crate_type = "dylib"]
 #![no_std]
 
 extern crate libc;
+extern crate compiler_builtins;
 
 #[no_mangle]
 pub extern fn bar() {}

src/test/run-make/no-duplicate-libs/foo.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(lang_items, libc)]
+#![feature(lang_items, libc, compiler_builtins_lib)]
 #![no_std]
 #![crate_type = "dylib"]
 
 extern crate libc;
+extern crate compiler_builtins;
 
 #[no_mangle]
 pub extern fn foo() {}