sys_sem_free

/**
 * Destroys a semaphore.
 *
 * @param sem is the semaphore to be destroyed.
 */
void
sys_sem_free(sys_sem_t *sem)
{
    u32_t i;

      /* Find a semaphore that is in use. */
      for(i = 0; i < SYS_SEM_MAX; i++) {
        if(sems[i].queue == sem->queue) {
          break;
        }
      }

    /* Delete Sem , By Jin */
      vQueueDelete(sem->queue);

      /* Clear the queue handle. */
      sem->queue = 0;
      /* Clear the queue handle in global array. */
      sems[i].queue = 0;

      /* Update the semaphore statistics. */
    #if SYS_STATS
      STATS_DEC(sys.sem.used);
    #endif /* SYS_STATS */
}