Remove unnecessary conditional cfg(target_os) for redox and vxworks

`redox` and `vxworks` are part of target_family `unix`, thus `cfg(unix)` already implies `cfg(target_os="redox")` and `(target_os="vxworks")`

Author: CDirkx

library/std/src/os/mod.rs

@@ -28,7 +28,7 @@ pub use crate::sys::wasi_ext as wasi;
 // If we're not documenting libstd then we just expose the main modules as we otherwise would.
 
 #[cfg(not(doc))]
-#[cfg(any(target_os = "redox", unix, target_os = "vxworks", target_os = "hermit"))]
+#[cfg(any(unix, target_os = "hermit"))]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use crate::sys::ext as unix;