Handle some stabilized rustc features

pcid/src/main.rs

@@ -1,6 +1,3 @@
-// Already stabilized, TODO: remove when Redox's rustc is updated
-#![feature(result_option_inspect)]
-
 use std::fs::{File, metadata, read_dir};
 use std::io::prelude::*;
 use std::os::unix::io::{FromRawFd, RawFd};

storage/virtio-blkd/src/main.rs

@@ -1,5 +1,5 @@
 #![deny(trivial_numeric_casts, unused_allocation)]
-#![feature(int_roundings, async_fn_in_trait)]
+#![feature(int_roundings)]
 
 // TODO(andypython): driver panic with an empty disk.