Shell: Don't pass nonsense options to waitpid()

I had these options confused with the options for waitid()

Shell/main.cpp

@@ -882,7 +882,7 @@ static int run_command(const String& cmd)
  for (size_t i = 0; i < children.size(); ++i) {
  auto& child = children[i];
  do {
- int rc = waitpid(child.pid, &wstatus, WEXITED | WSTOPPED);
+ int rc = waitpid(child.pid, &wstatus, 0);
  if (rc < 0 && errno != EINTR) {
  if (errno != ECHILD)
  perror("waitpid");