net: fix dead code warning

Signed-off-by: Sean Cross <sean@xobs.io>

library/std/src/sys/pal/xous/net/dns.rs

@@ -6,6 +6,7 @@
 use crate::os::xous::services::{DnsLendMut, dns_server};
 
 pub struct DnsError {
+    #[allow(dead_code)]
     pub code: u8,
 }
 

library/std/src/sys/pal/xous/net/mod.rs

@@ -60,6 +60,7 @@ pub struct in_addr {
 
     #[derive(Copy, Clone)]
     pub struct sockaddr_in {
+        #[allow(dead_code)]
         pub sin_family: sa_family_t,
         pub sin_port: u16,
         pub sin_addr: in_addr,
@@ -72,6 +73,7 @@ pub struct in6_addr {
 
     #[derive(Copy, Clone)]
     pub struct sockaddr_in6 {
+        #[allow(dead_code)]
         pub sin6_family: sa_family_t,
         pub sin6_port: u16,
         pub sin6_addr: in6_addr,