fix unknown vendor issue

src/wasi/mod.rs

@@ -1,6 +1,8 @@
 // [wasi-libc](https://github.com/WebAssembly/wasi-libc) definitions.
 // `wasi-libc` project provides multiple libraries including emulated features, but we list only basic features with `libc.a` here.
 
+#![allow(unexpected_cfgs)]
+
 use super::{Send, Sync};
 use core::iter::Iterator;
 
@@ -889,7 +891,6 @@ cfg_if! {
     }
 }
 
-#[allow(unexpected_cfgs)]
 cfg_if! {
     if #[cfg(target_vendor = "wasmer")] {
         mod wasix;

src/wasi/wasi.rs

@@ -1 +1,3 @@
+use super::c_uchar;
+
 pub type sigset_t = c_uchar;