sys::socket adding sockopt::LingerSec for Apple targets.

```
```

src/sys/socket/sockopt.rs

@@ -372,6 +372,16 @@ sockopt_impl!(
     libc::SO_LINGER,
     libc::linger
 );
+#[cfg(apple_targets)]
+sockopt_impl!(
+    /// `SO_LINGER_SEC` on apple targets is the genuine equivalent to
+    /// other platforms `SO_LINGER`. Indeed, the latter uses ticks.
+    LingerSec,
+    Both,
+    libc::SOL_SOCKET,
+    libc::SO_LINGER_SEC,
+    libc::linger
+);
 #[cfg(feature = "net")]
 sockopt_impl!(
     #[cfg_attr(docsrs, doc(cfg(feature = "net")))]

test/sys/test_sockopt.rs

@@ -1097,6 +1097,36 @@ mod sockopt_impl {
         assert_eq!(get_linger.l_linger, set_linger.l_linger);
     }
 
+    #[cfg(apple_targets)]
+    sockopt_impl!(
+        LingerSec,
+        Both,
+        libc::SOL_SOCKET,
+        libc::SO_LINGER_SEC,
+        libc::linger
+    );
+
+    #[cfg(apple_targets)]
+    #[test]
+    fn test_linger_sec() {
+        let fd = socket(
+            AddressFamily::Inet,
+            SockType::Stream,
+            SockFlag::empty(),
+            None,
+        )
+        .unwrap();
+
+        let set_linger = libc::linger {
+            l_onoff: 1,
+            l_linger: 1,
+        };
+        setsockopt(&fd, LingerSec, &set_linger).unwrap();
+
+        let get_linger = getsockopt(&fd, Linger).unwrap();
+        assert_eq!(get_linger.l_linger, set_linger.l_linger * 100);
+    }
+
     sockopt_impl!(KeepAlive, Both, libc::SOL_SOCKET, libc::SO_KEEPALIVE, bool);
 
     #[test]