Pass correct argument to rustc -Z ls

Behavior was changed back in rustc 1.74.

Fixes #2290

src/compiler/rust.rs

@@ -2372,7 +2372,7 @@ impl RlibDepReader {
         trace!("Discovering dependencies of {}", rlib.display());
 
         let mut cmd = process::Command::new(&self.executable);
-        cmd.args(["-Z", "ls"])
+        cmd.args(["-Z", "ls=root"])
             .arg(rlib)
             .env_clear()
             .envs(env_vars.to_vec())