Take sys/vxworks/stdio from sys/unix instead.

Author: m-ou-se

library/std/src/sys/vxworks/mod.rs

@@ -30,6 +30,7 @@ pub mod rand;
 pub mod rwlock;
 #[path = "../unix/stack_overflow.rs"]
 pub mod stack_overflow;
+#[path = "../unix/stdio.rs"]
 pub mod stdio;
 #[path = "../unix/thread.rs"]
 pub mod thread;