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

crypto/random_pool.c

@@ -509,7 +509,7 @@ void up_rngreseed(void)
       rng_reseed();
     }
 
-  sem_post(&g_rng.rd_sem);
+  nxsem_post(&g_rng.rd_sem);
 }
 
 /****************************************************************************
@@ -557,5 +557,5 @@ void getrandom(FAR void *bytes, size_t nbytes)
     }
 
   rng_buf_internal(bytes, nbytes);
-  sem_post(&g_rng.rd_sem);
+  nxsem_post(&g_rng.rd_sem);
 }