Sorry, this broke `target extended-remote' if the stub reports that
it isn't controlling any process yet (gdbserver --multi).  I missed
that there's a return statement in the middle of remote_start_remote,
which makes us not send '!' in that case.

remote_start_remote:
  if (rs->buf[0] == 'W' || rs->buf[0] == 'X')
    {
      if (args->extended_p)
	{
	  /* We're connected, but not running.  Drop out before we
	     call start_remote.  */
	  target_mark_exited (args->target);
	  return;
	}

Fixed by just sending '!' earlier, like below.  Checked in.

We should have a test for extended/persistent connections.  Let me
cook something up.

-- 
Pedro Alves