fix: move os_str into sys

library/std/src/sys/pal/zkvm/mod.rs

@@ -22,8 +22,6 @@ pub mod net;
 #[path = "../unsupported/once.rs"]
 pub mod once;
 pub mod os;
-#[path = "../unix/os_str.rs"]
-pub mod os_str;
 #[path = "../unix/path.rs"]
 pub mod path;
 #[path = "../unsupported/pipe.rs"]