text: pthread_rwlock_destroy()
  Destroy a read-write lock
  Synopsis:
  #include <pthread.h> int pthread_rwlock_destroy( pthread_rwlock_t* rwl );
  Arguments:
  - rwl
  - A pointer to a pthread_rwlock_t object that you want to destroy.
  Library:
  libc
  Use the -l c option to qcc to link against this library. This library is usually included automatically.
  Description:
  The pthread_rwlock_destroy() function destroys the read-write lock referenced by rwl, and releases the system resources used by the lock. You can destroy the read-write lock if one of the following is true:
  - no thread has a active shared or exclusive lock on rwl
  - the calling thread has an active exclusive lock on rwl.
  After successfully destroying a read-write lock, don't use it again without reinitializing it by calling pthread_rwlock_init() .
  Returns:
  - EOK
  - Success.
  - EBUSY
  - The read-write lock rwl is still in use. The calling thread doesn't have an exclusive lock.