Add SO_BINDTODEVICE sockopt

This is available only on Linux as far I know,
[socket(7)](https://linux.die.net/man/7/socket) has some information
about the `SO_BINDTODEVICE` sockopt. In simple words it binds a socket
to an specific network device (specified as an string like "wlo1",
"eth0", etc.), to only process packets from that device.

Signed-off-by: Jean Pierre Dudey <jeandudey@hotmail.com>

src/sys/socket/sockopt.rs

@@ -259,6 +259,8 @@ sockopt_impl!(SetOnly, RcvBufForce, libc::SOL_SOCKET, libc::SO_RCVBUFFORCE, usiz
 sockopt_impl!(SetOnly, SndBufForce, libc::SOL_SOCKET, libc::SO_SNDBUFFORCE, usize);
 sockopt_impl!(GetOnly, SockType, libc::SOL_SOCKET, libc::SO_TYPE, super::SockType);
 sockopt_impl!(GetOnly, AcceptConn, libc::SOL_SOCKET, libc::SO_ACCEPTCONN, bool);
+#[cfg(target_os = "linux")]
+sockopt_impl!(Both, BindToDevice, libc::SOL_SOCKET, libc::SO_BINDTODEVICE, OsString<[u8; libc::IFNAMSIZ]>);
 #[cfg(any(target_os = "android", target_os = "linux"))]
 sockopt_impl!(GetOnly, OriginalDst, libc::SOL_IP, libc::SO_ORIGINAL_DST, libc::sockaddr_in);
 sockopt_impl!(Both, ReceiveTimestamp, libc::SOL_SOCKET, libc::SO_TIMESTAMP, bool);