/scheme/sys/uname: include the "version" info

With this change, we use the recently-added `COOKBOOK_TIME_IDENT`
environment variable at compile time to get the "version" info for the
uname scheme. This field is unspecified by POSIX what it should have,
but most kernels (including Linux, XNU, NetBSD, etc.) put the build
time here.

src/scheme/sys/uname.rs

@@ -3,9 +3,10 @@ use alloc::vec::Vec;
 
 pub fn resource(_token: &mut CleanLockToken) -> Result<Vec<u8>> {
     Ok(format!(
-        "Redox\n\n{}\n\n{}\n",
+        "Redox\n{}\n{}\n{}\n",
         env!("CARGO_PKG_VERSION"),
-        env!("TARGET").split('-').next().unwrap()
+        env!("TARGET").split('-').next().unwrap(),
+        env!("COOKBOOK_TIME_IDENT")
     )
     .into_bytes())
 }