1: - we should probably extend pthread_mutexattr_t with a field to create a
    2:   single linked list of all instances.  This requires changing the
    3:   pthread_mutexattr_* functions.
    4: 
    5: 
    6: - a new attribute for mutexes: number of times we spin before calling
    7: sys_futex
    8: 
    9: - for adaptive mutexes: when releasing, determine whether somebody spins.
   10: If yes, for a short time release lock.  If someone else locks no wakeup
   11: syscall needed.
   12: 
   13: 
   14: 
   15: - test with threaded process terminating and semadj (?) being applied
   16:   only after all threads are gone
   17: 
   18: 
   19: 
   20: - semaphore changes:
   21: 
   22:   - sem_post should only wake one thread and only when the state of
   23:     the semaphore changed from 0 to 1
   24: 
   25:     this also requires that sem_wait and sem_timedwait don't drop the
   26:     post if they get canceled.
   27: 
   28:   - possibly add counter field.  This requires reviving the
   29:     differences between old and new semaphose funtions.  The old ones
   30:     stay as they are now.  The new once can use an additional field
   31:     wich is the counter for the number of waiters