Squashed commit of the following:

sched/semaphore:  Add nxsem_post() which is identical to sem_post() except that it never modifies the errno variable.  Changed all references to sem_post in the OS to nxsem_post().

    sched/semaphore:  Add nxsem_destroy() which is identical to sem_destroy() except that it never modifies the errno variable.  Changed all references to sem_destroy() in the OS to nxsem_destroy().

    libc/semaphore and sched/semaphore:  Add nxsem_getprotocol() and nxsem_setprotocola which are identical to sem_getprotocol() and set_setprotocol() except that they never modifies the errno variable.  Changed all references to sem_setprotocol in the OS to nxsem_setprotocol().  sem_getprotocol() was not used in the OS

drivers/mmcsd/mmcsd_spi.c

@@ -389,7 +389,7 @@ static void mmcsd_semgive(FAR struct mmcsd_slot_s *slot)
 {
   /* Relinquish the lock on the MMC/SD device */
 
-  sem_post(&slot->sem);
+  nxsem_post(&slot->sem);
 
   /* Relinquish the lock on the SPI bus */