Bug #40899 Mutex not unlocked in ndb_util_thread_func

Description:
In 5.1, in ha_ndb_cluster.cc, in ndb_util_thread_func(),
the code contain at the beginning:

   pthread_mutex_lock(&LOCK_ndb_util_thread);

  thd= new THD; /* note that contructor of THD uses DBUG_ */
  if (thd == NULL)
  {
    my_errno= HA_ERR_OUT_OF_MEM;
    DBUG_RETURN(NULL);
  }

If the server is out of memory (which might happen under normal operations if we implement per thread memory quotas), this function returns while holding a lock on the LOCK_ndb_util_thread mutex.

Note that fix bug exist in 5.1 and 6.0, but not in 5.0,
so technically this is a risk of regression with a dead lock.

How to repeat:
Code review

Suggested fix:
Fix the indentation
Fix the comments typos
Allocate THD before locking the mutex, which will make the critical section smaller as well.

Should be an unlock when exiting, but not during run time/per martin