Eliminate non-standard NULL definitions

Revises kernel so that it uses the standard NULL symbol defined
for C99, rather than having its own custom symbol.

Change-Id: I74342f192e95899a83db879e8b1c8fe89ac8b92d
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>

arch/x86/include/nanok.h

@@ -744,10 +744,6 @@ typedef struct s_NANO {
 #define STACK_ROUND_UP(x) ROUND_UP(x, STACK_ALIGN_SIZE)
 #define STACK_ROUND_DOWN(x) ROUND_DOWN(x, STACK_ALIGN_SIZE)
 
-#ifndef NULL
-#define NULL (void *)0
-#endif
-
 /* variable declarations */
 
 /*

include/misc/lists.h

@@ -54,11 +54,6 @@ struct List {
 };
 
 
-
-#ifndef NULL
-#define NULL (void *)0
-#endif
-
 #ifndef INLINED
 extern void InitList(struct list_head *list);
 extern unsigned int TestListEmpty(struct list_head *list);

include/misc/util.h

@@ -58,10 +58,6 @@ extern "C" {
 #define INLINE
 #endif
 
-#ifndef NULL
-#define NULL ((void *)0)
-#endif
-
 #ifndef max
 #define max(a, b) (((a) > (b)) ? (a) : (b))
 #endif

include/nanokernel.h

@@ -33,6 +33,7 @@
 #ifndef __NANOKERNEL_H__
 #define __NANOKERNEL_H__
 
+#include <stddef.h>
 #include <stdint.h>
 #include <toolchain.h> /* compiler specific configuration options */
 

kernel/microkernel/include/minik.h

@@ -33,6 +33,7 @@
 #ifndef MINIK_H
 #define MINIK_H
 
+#include <stddef.h>
 #include <kernel_struct.h>
 #include <kernel_main.h>
 #include <clock_vars.h>