fix unused import warning on windows

src/machine/streams.rs

@@ -23,7 +23,7 @@ use std::fmt::Debug;
 use std::fs::{File, OpenOptions};
 use std::hash::Hash;
 use std::io;
-use std::io::{Cursor, ErrorKind, IsTerminal, Read, Seek, SeekFrom, Write};
+use std::io::{Cursor, ErrorKind, Read, Seek, SeekFrom, Write};
 use std::mem::ManuallyDrop;
 use std::net::{Shutdown, TcpStream};
 use std::ops::{Deref, DerefMut};
@@ -657,6 +657,8 @@ impl Stream {
 
     #[inline]
     pub fn stdin(arena: &mut Arena, add_history: bool) -> Stream {
+        #[cfg(unix)]
+        use std::io::IsTerminal;
         #[cfg(unix)]
         if !std::io::stdin().is_terminal() {
             use std::os::unix::io::{FromRawFd, RawFd};