wctype.h needs extern C

include/cxx/cwctype

@@ -48,7 +48,9 @@
 
 namespace std
 {
+  using ::wint_t;
   using ::wctrans_t;
+  using ::wctype_t;
 
   using ::iswalnum;
   using ::iswalpha;

include/wctype.h

@@ -81,6 +81,14 @@ typedef int wctrans_t;
  * Public Function Prototypes
  ****************************************************************************/
 
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
 /* "The <wchar.h> header declares the following as functions and may also
  *  define them as macros. Function prototypes must be provided for use with
  *  an ISO C compiler."
@@ -108,4 +116,9 @@ wctrans_t         wctrans(FAR const char *);
 int               iswctype(wint_t, wctype_t);
 wctype_t          wctype(FAR const char *);
 
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* INCLUDE_WTYPE_H */