bugfix: Fix unused type in WASI (#1177)

Signed-off-by: John Nunley <dev@notgull.net>

Author: notgull

src/backend/libc/termios/types.rs

@@ -11,5 +11,5 @@ use crate::ffi;
 pub type tcflag_t = ffi::c_ulong;
 #[cfg(target_os = "redox")]
 pub type tcflag_t = u32;
-#[cfg(not(any(apple, target_os = "redox")))]
+#[cfg(not(any(target_os = "wasi", apple, target_os = "redox")))]
 pub type tcflag_t = ffi::c_uint;