Fix <locale.h> not defining NULL.

libc/include/locale.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2015 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2012, 2015, 2017 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -22,10 +22,9 @@
 
 #include <sys/cdefs.h>
 
-#include <sys/__/types.h>
-
-#ifdef __cplusplus
-extern "C" {
+#ifndef NULL
+#define __need_NULL
+#include <stddef.h>
 #endif
 
 struct lconv
@@ -65,6 +64,10 @@ struct lconv
 #define LC_ALL 6
 #define LC_NUM_CATEGORIES LC_ALL
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 char* setlocale(int category, const char* locale);
 struct lconv* localeconv(void);