feat(socket): add AF_UNSPEC

Author: mkroening

src/syscalls/socket.rs

@@ -24,6 +24,7 @@ use crate::fd::{
 };
 use crate::syscalls::block_on;
 
+pub const AF_UNSPEC: i32 = 0;
 pub const AF_INET: i32 = 0;
 pub const AF_INET6: i32 = 1;
 pub const AF_VSOCK: i32 = 2;