mysql-test-run runs with --sleep=10; otherwise GET_LOCK() times out
before being killed so we get 0 instead of NULL. Verified that it
works on our powermacg5 where the test was failing.


mysql-test/t/kill.test:
  must always sleep 2 seconds, even if mysql-test-run runs with --sleep=10;
  otherwise GET_LOCK() times out before being killed so we get 0 instead of NULL.