Add `wake_trait` feature directive to std

src/libstd/lib.rs

@@ -310,6 +310,7 @@
 #![feature(untagged_unions)]
 #![feature(unwind_attributes)]
 #![feature(vec_into_raw_parts)]
+#![feature(wake_trait)]
 // NB: the above list is sorted to minimize merge conflicts.
 #![default_lib_allocator]