Address several issues from compiling examples

Compiling the code from examples "code-block:: c" along with public
includes and a bsp exposed a few issues amongst a lot of false
positives. Address some of these:

* Terminate struct declarations with ';'. Mainly for pedantic
  correctness.

* Show ptrdiff_t instead of size_t for the sbrk() prototype, matching
  the current argument type in rtems.

* Replace some occurrences of unsigned16 with uint16_t.

* Fix odd type declaration, "uint8_t char*" -> "char*".

* Use appropriate helper to get chain head instead of invalid access to
  nonexistent struct member.

* Remove several excess '\' escapes.

* Use RTEMS_SELF instead of undefined SELF.

* Use rtems_task instead of void for task functions.

* Add missing stack size parameter in task creation.

* Use rtems_interrupt_level instead of undefined rtems_interrupt.

* Correct return value format for rtems_object_id_get_api()
  rtems_object_id_get_index() (enum and uint16_t) and also fix
  corresponding print formatting.

* Correct return value documentation for rtems_object_id_get_class(),
  rtems_object_id_get_node() and rtems_object_id_get_index()
  int -> uint32_t.

* Use RTEMS_SUCCESSFUL instead of undefined RTEMS_STATUS_SUCCESSFUL and
  fix return value variable name in rate monotonic examples.

* Use RTEMS_TIMEOUT instead of undefined TIMEOUT and RTEMS_PERIOD_STATUS
  instead of undefined STATUS.

* Add missing fields to ftpd configuration.

* Correct parameter types in ftpd hook prototype,
  unsigned char * -> void *.

* Fix various code-block:: attributes, c -> makefile and c -> shell.

* Add missing parenthesis in socket buffer memory calculation example.

* Remove typedef in declaration of mq_attr since it is defiend without
  typedef in reality.

* Update siginfo_t declaration to match current reality.

* Update shell user command definition example to include mode, uid and
  gid.

bsp-howto/console.rst

@@ -168,7 +168,7 @@ The handler table for the polled mode should look like the following.
       .set_attributes = my_driver_set_attributes,
       .ioctl = my_driver_ioctl, /* optional, may be NULL */
       .mode = TERMIOS_POLLED
-    }
+    };
 
 The :c:func:`my_driver_poll_write()` routine is responsible for writing ``n``
 characters from ``buf`` to the serial device specified by ``base``.

bsp-howto/miscellanous_support.rst

@@ -138,7 +138,7 @@ prototype for this routine:
 
 .. code-block:: c
 
-    void * sbrk(size_t increment)
+    void * sbrk(ptrdiff_t increment)
 
 The ``increment`` amount is based upon the ``sbrk_amount`` parameter passed to
 the ``bsp_libc_init`` during system initialization.

bsp-howto/real_time_clock.rst

@@ -67,8 +67,8 @@ table is below:
 
     bool dmv177_icm7170_probe(int minor)
     {
-      volatile unsigned16 *card_resource_reg;
-      card_resource_reg = (volatile unsigned16 *) DMV170_CARD_RESORCE_REG;
+      volatile uint16_t *card_resource_reg;
+      card_resource_reg = (volatile uint16_t *) DMV170_CARD_RESORCE_REG;
       if ( (*card_resource_reg & DMV170_RTC_INST_MASK) == DMV170_RTC_INSTALLED )
         return TRUE;
       return FALSE;