[PATCH 5/5] include: Fix conflicting definitions of NULL, wchar_t, wint_t, wctype_t.

[Puetz Kevin A]

When <basetyps.h> defines wchar_t, it must obey -f(no-)short-wchar
by referring to __WCHAR_TYPE__ which may not be `unsigned short`.
Similarly, windef.h defining NULL may need to use GCC's __null.
Otherwise one-definition-rule problems arise depending on whether
wine or libc headers are included first.

Implementing these by deferring to the C89-specified libc headers,
(or msvcrt's versions with -mno-cygwin) ensures matching definitions.

Signed-off-by: Kevin Puetz <PuetzKevinA at JohnDeere.com>
---
 include/basetyps.h |  8 +++++---
 include/tchar.h    |  9 +--------
 include/windef.h   | 11 +++++++----
 3 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/include/basetyps.h b/include/basetyps.h
index b0dd5d77f4..e6243d5a59 100644
--- a/include/basetyps.h
+++ b/include/basetyps.h
@@ -91,9 +91,11 @@ typedef unsigned long error_status_t;
 #endif
 
 #ifndef _WCHAR_T_DEFINED
-#ifndef __cplusplus
-typedef unsigned short wchar_t;
-#endif
+# ifndef __cplusplus
+#  define __need_wchar_t // tells GCC's stddef.h to only define wchar_t
+#  include <stddef.h>
+#  undef __need_wchar_t
+# endif
 #define _WCHAR_T_DEFINED
 #endif
 
diff --git a/include/tchar.h b/include/tchar.h
index 6c9035c219..0049ea7e7a 100644
--- a/include/tchar.h
+++ b/include/tchar.h
@@ -232,14 +232,7 @@ extern "C" {
 #endif /* tchar mappings */
 
 #ifdef _UNICODE
-#if !defined(_WINT_T_DEFINED) && !defined(__WINT_TYPE__)
-typedef unsigned short wint_t;
-#endif
-
-#ifndef _WCTYPE_T_DEFINED
-typedef unsigned short wctype_t;
-#define _WCTYPE_T_DEFINED
-#endif
+#include <wchar.h>
 
 #ifndef __TCHAR_DEFINED
 #if defined(WINE_UNICODE_NATIVE)
diff --git a/include/windef.h b/include/windef.h
index 521c3ab451..e26ffe6ff4 100644
--- a/include/windef.h
+++ b/include/windef.h
@@ -206,11 +206,14 @@ extern "C" {
 
 /* Misc. constants. */
 
-#undef NULL
-#ifdef __cplusplus
-#define NULL  0
-#else
+#ifndef NULL
+#ifdef RC_INVOKED
 #define NULL  ((void*)0)
+#else
+#define __need_NULL // tells GCC's stddef.h to only define NULL
+#include <stddef.h>
+#undef __need_NULL
+#endif
 #endif
 
 #ifdef FALSE