message: Fix wexitstatus function
diff: @@ -101,7 +101,7 @@ pub(crate) fn watch_foreground(shell: &mut Shell, pid: i32, command: &str) -> i3
  }
  },
  Ok(0) => (),
  - Ok(_pid) if wifexited(status) => exit_status = WEXITSTATUS(status),
  + Ok(_pid) if wifexited(status) => exit_status = wexitstatus(status),
  Ok(pid) if wifsignaled(status) => {
  let signal = wtermsig(status);
  if signal == SIGPIPE {
  