lib: remove array_chunks nightly feature

Removes the nightly `array_chunks` feature, since it is marked as
unlikely to be merged.

Usage is trivially refactored using iterators.

redox-rt/src/lib.rs

@@ -1,7 +1,6 @@
 #![no_std]
 #![feature(
     asm_const,
-    array_chunks,
     core_intrinsics,
     int_roundings,
     let_chains,

redox-rt/src/proc.rs

@@ -715,11 +715,10 @@ pub fn create_set_addr_space_buf(
     ip: usize,
     sp: usize,
 ) -> [u8; size_of::<usize>() * 3] {
-    let mut buf = [0_u8; 3 * size_of::<usize>()];
-    let mut chunks = buf.array_chunks_mut::<{ size_of::<usize>() }>();
-    *chunks.next().unwrap() = usize::to_ne_bytes(space);
-    *chunks.next().unwrap() = usize::to_ne_bytes(sp);
-    *chunks.next().unwrap() = usize::to_ne_bytes(ip);
+    let mut buf = [0u8; size_of::<usize>() * 3];
+
+    buf.copy_from_slice([space, sp, ip].map(usize::to_ne_bytes).as_flattened());
+
     buf
 }
 

src/lib.rs

@@ -13,7 +13,6 @@
 #![allow(unused_variables)]
 #![feature(alloc_error_handler)]
 #![feature(allocator_api)]
-#![feature(array_chunks)]
 #![feature(asm_const)]
 #![feature(c_variadic)]
 #![feature(core_intrinsics)]