move wchar_t to stddef header

include/stddef.h

@@ -1,6 +1,19 @@
 #ifndef _STDDEF_H
 #define _STDDEF_H
 #include <stdint.h>
+
+// wchar_t should come before NULL and size_t
+// according to comment in wchar cbindgen
+#ifndef _WCHAR_T
+#define _WCHAR_T
+#ifndef __cplusplus
+    #ifndef __WCHAR_TYPE__
+        #define __WCHAR_TYPE__ int32_t
+    #endif
+    typedef __WCHAR_TYPE__ wchar_t;
+#endif // __cplusplus
+#endif // _WCHAR_T
+
 #include <bits/size-t.h>
 
 #define NULL 0

src/header/wchar/cbindgen.toml

@@ -4,19 +4,9 @@ sys_includes = [
     "features.h",
 ]
 after_includes = """
-// int32_t, uint32_t, WCHAR_MIN, WCHAR_MAX
+// uint32_t, WCHAR_MIN, WCHAR_MAX
 #include <stdint.h>
 
-#ifndef _WCHAR_T
-#define _WCHAR_T
-#ifndef __cplusplus
-    #ifndef __WCHAR_TYPE__
-        #define __WCHAR_TYPE__ int32_t
-    #endif
-    typedef __WCHAR_TYPE__ wchar_t;
-#endif // __cplusplus
-#endif // _WCHAR_T
-
 #ifndef _WINT_T
 #define _WINT_T
     #ifndef __WINT_TYPE__