MacBook Pro 2018 6-core i7 when running "cargo build --release"
fi-0.0.1/src/lib.rs:2:1
  |
2 | #![feature(libc)]
  | ^^^^^^^^^^^^^^^^^

error[E0554]: #![feature] may not be used on the stable release channel

error: aborting due to previous error

For more information about this error, try `rustc --explain E0554`.
error: aborting due to previous error

For more information about this error, try `rustc --explain E0554`.
error: Could not compile `skein-ffi`.
warning: build failed, waiting for other jobs to finish...
error: Could not compile `jh-ffi`.

To learn more, run the command again with --verbose.
