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/input/stmpe811_tsc.c

@@ -181,7 +181,7 @@ static void stmpe811_notify(FAR struct stmpe811_dev_s *priv)
        * is no longer available.
        */
 
-      sem_post(&priv->waitsem);
+      nxsem_post(&priv->waitsem);
     }
 
   /* If there are threads waiting on poll() for STMPE811 data to become available,
@@ -198,7 +198,7 @@ static void stmpe811_notify(FAR struct stmpe811_dev_s *priv)
         {
           fds->revents |= POLLIN;
           iinfo("Report events: %02x\n", fds->revents);
-          sem_post(fds->sem);
+          nxsem_post(fds->sem);
         }
     }
 #endif
@@ -289,7 +289,7 @@ static inline int stmpe811_waitsample(FAR struct stmpe811_dev_s *priv,
    * run, but they cannot run yet because pre-emption is disabled.
    */
 
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
 
   /* Try to get the a sample... if we cannot, then wait on the semaphore
    * that is posted when new sample data is available.
@@ -395,7 +395,7 @@ static int stmpe811_open(FAR struct file *filep)
   priv->crefs = tmp;
 
 errout_with_sem:
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
   return ret;
 #else
   return OK;
@@ -444,7 +444,7 @@ static int stmpe811_close(FAR struct file *filep)
       priv->crefs--;
     }
 
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
 #endif
   return OK;
 }
@@ -574,7 +574,7 @@ static ssize_t stmpe811_read(FAR struct file *filep, FAR char *buffer, size_t le
   ret = SIZEOF_TOUCH_SAMPLE_S(1);
 
 errout:
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
   return ret;
 }
 
@@ -635,7 +635,7 @@ static int stmpe811_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
         break;
     }
 
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
   return ret;
 }
 
@@ -732,7 +732,7 @@ static int stmpe811_poll(FAR struct file *filep, FAR struct pollfd *fds,
     }
 
 errout:
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
   return ret;
 }
 #endif
@@ -919,7 +919,7 @@ int stmpe811_register(STMPE811_HANDLE handle, int minor)
   if ((priv->inuse & TSC_PIN_SET) != 0)
     {
       ierr("ERROR: TSC pins is already in-use: %02x\n", priv->inuse);
-      sem_post(&priv->exclsem);
+      nxsem_post(&priv->exclsem);
       return -EBUSY;
     }
 
@@ -936,7 +936,7 @@ int stmpe811_register(STMPE811_HANDLE handle, int minor)
   if (!priv->wdog)
     {
       ierr("ERROR: Failed to create a watchdog\n", errno);
-      sem_post(&priv->exclsem);
+      nxsem_post(&priv->exclsem);
       return -ENOSPC;
     }
 
@@ -947,7 +947,7 @@ int stmpe811_register(STMPE811_HANDLE handle, int minor)
   if (ret < 0)
     {
       ierr("ERROR: Failed to register driver %s: %d\n", devname, ret);
-      sem_post(&priv->exclsem);
+      nxsem_post(&priv->exclsem);
       return ret;
     }
 
@@ -959,7 +959,7 @@ int stmpe811_register(STMPE811_HANDLE handle, int minor)
 
   priv->inuse |= TSC_PIN_SET;                    /* Pins 4-7 are now in-use */
   priv->flags |= STMPE811_FLAGS_TSC_INITIALIZED;  /* TSC function is initialized */
-  sem_post(&priv->exclsem);
+  nxsem_post(&priv->exclsem);
   return ret;
 }