fix const in arr expression

experiments/src/main.rs

@@ -1,6 +1,5 @@
 #![no_std]
 #![no_main]
-#![feature(const_in_array_repeat_expressions)]
 #![feature(naked_functions)]
 
 extern crate alloc;

libcortex_a9/src/lib.rs

@@ -1,6 +1,5 @@
 #![no_std]
 #![feature(never_type)]
-#![feature(const_fn)]
 
 extern crate alloc;
 

libcortex_a9/src/sync_channel.rs

@@ -172,7 +172,6 @@ impl<'a, T> Iterator for Receiver<'a, T> where T: Clone {
 
 #[macro_export]
 /// Macro for initializing the sync_channel with static buffer and indexes.
-/// Note that this requires `#![feature(const_in_array_repeat_expressions)]`
 macro_rules! sync_channel {
     ($t: ty, $cap: expr) => {
         {