Merge gbichot@bk-internal.mysql.com:/home/bk/mysql-4.1

    least the first step above)

  global_read_lock_blocks_commit

    count of threads which have the global read lock and block

    commits (i.e. have completed the second step above)

    commits (i.e. are in or have completed the second step above)

  waiting_for_read_lock

    count of threads which want to take a global read lock but cannot

  protect_against_global_read_lock

  if (unlikely(thd->global_read_lock))

    DBUG_VOID_RETURN;

  (void) pthread_mutex_lock(&LOCK_open);

  tmp= (!--protect_against_global_read_lock && waiting_for_read_lock);

  tmp= (!--protect_against_global_read_lock &&

        (waiting_for_read_lock || global_read_lock_blocks_commit));

  (void) pthread_mutex_unlock(&LOCK_open);

  if (tmp)

    pthread_cond_broadcast(&COND_refresh);