Squashed commit of the following:

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

    sched/semaphore:  Rename all internal private functions from sem_xyz to nxsem_xyz.  The sem_ prefix is (will be) reserved only for the application semaphore interfaces.

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

    sched/semaphore:  Rename sem_tickwait() to nxsem_tickwait() so that it is clear this is an internal OS function.

    sched/semaphoate:  Rename sem_reset() to nxsem_reset() so that it is clear this is an internal OS function.

drivers/input/ads7843e.c

@@ -1190,8 +1190,8 @@ int ads7843e_register(FAR struct spi_dev_s *spi,
 
   /* Initialize semaphores */
 
-  sem_init(&priv->devsem,  0, 1);    /* Initialize device structure semaphore */
-  sem_init(&priv->waitsem, 0, 0);    /* Initialize pen event wait semaphore */
+  nxsem_init(&priv->devsem,  0, 1);    /* Initialize device structure semaphore */
+  nxsem_init(&priv->waitsem, 0, 0);    /* Initialize pen event wait semaphore */
 
   /* The pen event semaphore is used for signaling and, hence, should not
    * have priority inheritance enabled.

drivers/input/ajoystick.c

@@ -873,7 +873,7 @@ int ajoy_register(FAR const char *devname,
   /* Initialize the new ajoystick driver instance */
 
   priv->au_lower = lower;
-  sem_init(&priv->au_exclsem, 0, 1);
+  nxsem_init(&priv->au_exclsem, 0, 1);
 
   DEBUGASSERT(lower->al_buttons);
   priv->au_sample = lower->al_buttons(lower);

drivers/input/button_upper.c

@@ -855,7 +855,7 @@ int btn_register(FAR const char *devname,
   /* Initialize the new button driver instance */
 
   priv->bu_lower = lower;
-  sem_init(&priv->bu_exclsem, 0, 1);
+  nxsem_init(&priv->bu_exclsem, 0, 1);
 
   DEBUGASSERT(lower->bl_buttons);
   priv->bu_sample = lower->bl_buttons(lower);

drivers/input/cypress_mbr3108.c

@@ -1136,7 +1136,7 @@ int cypress_mbr3108_register(FAR const char *devpath,
   priv->board = board_config;
   priv->sensor_conf = sensor_conf;
 
-  sem_init(&priv->devsem, 0, 1);
+  nxsem_init(&priv->devsem, 0, 1);
 
   ret = register_driver(devpath, &g_mbr3108_fileops, 0666, priv);
   if (ret < 0)

drivers/input/djoystick.c

@@ -869,7 +869,7 @@ int djoy_register(FAR const char *devname,
   /* Initialize the new djoystick driver instance */
 
   priv->du_lower = lower;
-  sem_init(&priv->du_exclsem, 0, 1);
+  nxsem_init(&priv->du_exclsem, 0, 1);
 
   DEBUGASSERT(lower->dl_sample);
   priv->du_sample = lower->dl_sample(lower);

drivers/input/max11802.c

@@ -1193,8 +1193,8 @@ int max11802_register(FAR struct spi_dev_s *spi,
 
   /* Initialize semaphores */
 
-  sem_init(&priv->devsem,  0, 1);    /* Initialize device structure semaphore */
-  sem_init(&priv->waitsem, 0, 0);    /* Initialize pen event wait semaphore */
+  nxsem_init(&priv->devsem,  0, 1);    /* Initialize device structure semaphore */
+  nxsem_init(&priv->waitsem, 0, 0);    /* Initialize pen event wait semaphore */
 
   /* The pen event semaphore is used for signaling and, hence, should not
    * have priority inheritance enabled.

drivers/input/mxt.c

@@ -1905,8 +1905,8 @@ int mxt_register(FAR struct i2c_master_s *i2c,
 
   /* Initialize semaphores */
 
-  sem_init(&priv->devsem, 0, 1);  /* Initialize device semaphore */
-  sem_init(&priv->waitsem, 0, 0); /* Initialize event wait semaphore */
+  nxsem_init(&priv->devsem, 0, 1);  /* Initialize device semaphore */
+  nxsem_init(&priv->waitsem, 0, 0); /* Initialize event wait semaphore */
 
   /* The event wait semaphore is used for signaling and, hence, should not
    * have priority inheritance enabled.

drivers/input/stmpe811_base.c

@@ -297,7 +297,7 @@ STMPE811_HANDLE stmpe811_instantiate(FAR struct i2c_master_s *dev,
 
   /* Initialize the device state structure */
 
-  sem_init(&priv->exclsem, 0, 1);
+  nxsem_init(&priv->exclsem, 0, 1);
   priv->config = config;
 
 #ifdef CONFIG_STMPE811_SPI

drivers/input/tsc2007.c

@@ -1255,8 +1255,8 @@ int tsc2007_register(FAR struct i2c_master_s *dev,
   memset(priv, 0, sizeof(struct tsc2007_dev_s));
   priv->i2c    = dev;             /* Save the I2C device handle */
   priv->config = config;          /* Save the board configuration */
-  sem_init(&priv->devsem,  0, 1); /* Initialize device structure semaphore */
-  sem_init(&priv->waitsem, 0, 0); /* Initialize pen event wait semaphore */
+  nxsem_init(&priv->devsem,  0, 1); /* Initialize device structure semaphore */
+  nxsem_init(&priv->waitsem, 0, 0); /* Initialize pen event wait semaphore */
 
   /* Make sure that interrupts are disabled */