relibc: extend getsockopt to handle IPPROTO_IP and IPPROTO_IPV6

Previously only SOL_SOCKET and IPPROTO_TCP levels were handled by
the socket scheme. Now IPPROTO_IP and IPPROTO_IPV6 levels also
forward to the socket scheme via SocketCall::GetSockOpt, removing
the ENOSYS fallthrough for these common socket option levels.

Cross-referenced with Linux 7.1 net/ipv4/ip_sockglue.c and
net/ipv6/ipv6_sockglue.c which implement IP/UDP/ICMP level
getsockopt handlers.

src/platform/redox/socket.rs

@@ -789,6 +789,22 @@ impl PalSocket for Sys {
                 }
                 return Ok(());
             }
+            crate::header::netinet_in::IPPROTO_IP as c_int
+            | crate::header::netinet_in::IPPROTO_IPV6 as c_int => {
+                let metadata = [SocketCall::GetSockOpt as u64, option_name as u64];
+                let payload =
+                    unsafe { slice::from_raw_parts_mut(option_value as *mut u8, option_len) };
+                let call_flags = CallFlags::empty();
+                unsafe {
+                    *option_len_ptr = redox_rt::sys::sys_call_ro(
+                        socket as usize,
+                        payload,
+                        CallFlags::empty(),
+                        &metadata,
+                    )? as socklen_t;
+                }
+                return Ok(());
+            }
             _ => (),
         }