Add 'feature' and 'since' to stability attributes

src/libstd/lib.rs

@@ -95,7 +95,7 @@
 //! and `format!`, also available to all Rust code.
 
 #![crate_name = "std"]
-#![stable]
+#![stable(feature = "grandfathered", since = "1.0.0")]
 #![staged_api]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
@@ -175,7 +175,7 @@ pub use alloc::rc;
 pub use core_collections::slice;
 pub use core_collections::str;
 pub use core_collections::string;
-#[stable]
+#[stable(feature = "grandfathered", since = "1.0.0")]
 pub use core_collections::vec;
 
 pub use unicode::char;