ProtocolType::Dns exists only if feature local-dns enabled

- fixes #469

bin/sslocal.rs

@@ -306,7 +306,7 @@ fn main() {
             }
         }
 
-        #[cfg(target_os = "android")]
+        #[cfg(all(feature = "local-dns", target_os = "android"))]
         if protocol != ProtocolType::Dns {
             // Start a DNS local server binding to DNS_LOCAL_ADDR
             //

crates/shadowsocks-service/src/sys/unix/mod.rs

@@ -1,8 +1,10 @@
-use std::io::{self, Error};
+use std::io;
 
 #[allow(dead_code)]
 #[cfg(not(target_os = "android"))]
 pub fn set_nofile(nofile: u64) -> io::Result<()> {
+    use std::io::Error;
+
     unsafe {
         // set both soft and hard limit
         let lim = libc::rlimit {