Command::env_saw_path() may be unused on platforms not using posix_sp…

…awn()

src/libstd/sys/unix/process/process_common.rs

@@ -184,6 +184,7 @@ impl Command {
         let maybe_env = self.env.capture_if_changed();
         maybe_env.map(|env| construct_envp(env, &mut self.saw_nul))
     }
+    #[allow(dead_code)]
     pub fn env_saw_path(&self) -> bool {
         self.env.have_changed_path()
     }