Share *RawFd trait implementations on Unix

They were previously only present on Apple platforms.

tun/src/unix/apple/mod.rs

@@ -1,11 +1,11 @@
 use fehler::throws;
 use libc::c_char;
-use std::net::Ipv4Addr;
-use std::os::unix::io::{AsRawFd, IntoRawFd, RawFd};
 use std::io::Error;
+use std::net::Ipv4Addr;
+use std::os::fd::AsRawFd;
 
-mod sys;
 mod kern_control;
+mod sys;
 
 pub use super::queue::TunQueue;
 
@@ -62,15 +62,3 @@ impl TunInterface {
         todo!()
     }
 }
-
-impl AsRawFd for TunInterface {
-    fn as_raw_fd(&self) -> RawFd {
-        self.socket.as_raw_fd()
-    }
-}
-
-impl IntoRawFd for TunInterface {
-    fn into_raw_fd(self) -> RawFd {
-        self.socket.into_raw_fd()
-    }
-}