Set unstable feature names appropriately

* `core` - for the core crate
* `hash` - hashing
* `io` - io
* `path` - path
* `alloc` - alloc crate
* `rand` - rand crate
* `collections` - collections crate
* `std_misc` - other parts of std
* `test` - test crate
* `rustc_private` - everything else

src/libfmt_macros/lib.rs

@@ -15,7 +15,7 @@
 //! generated instead.
 
 #![crate_name = "fmt_macros"]
-#![unstable(feature = "unnamed_feature")]
+#![unstable(feature = "rustc_private")]
 #![feature(staged_api)]
 #![staged_api]
 #![crate_type = "rlib"]
@@ -27,7 +27,9 @@
 
 #![feature(slicing_syntax)]
 #![allow(unknown_features)] #![feature(int_uint)]
-#![feature(unnamed_feature)]
+#![feature(collections)]
+#![feature(core)]
+#![feature(unicode)]
 
 pub use self::Piece::*;
 pub use self::Position::*;