includes: Provide `wchar.h` with `wchar_t` and `wint_t`

Change-Id: Iacb0e4eaf3f0b6bf843f3bfda5bdfde0f7a98808
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55590
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

payloads/libpayload/curses/curses.h

@@ -154,9 +154,9 @@ typedef unsigned long mmask_t;
 //// #define va_list int	// FIXME
 
 #define _XOPEN_SOURCE_EXTENDED 1	// XXX
-//// #ifdef _XOPEN_SOURCE_EXTENDED
-//// #include <stddef.h>	/* we want wchar_t */
-//// #endif /* _XOPEN_SOURCE_EXTENDED */
+#ifdef _XOPEN_SOURCE_EXTENDED
+#include <stddef.h>	/* we want wchar_t */
+#endif /* _XOPEN_SOURCE_EXTENDED */
 
 /* XSI and SVr4 specify that curses implements 'bool'.  However, C++ may also
  * implement it.  If so, we must use the C++ compiler's type to avoid conflict
@@ -350,9 +350,7 @@ typedef	chtype	attr_t;		/* ...must be at least as wide as chtype */
 #endif
 
 #if 1
-//// #include <wchar.h>		/* ...to get mbstate_t, etc. */
-typedef unsigned long wchar_t;	// XXX
-typedef unsigned long wint_t;	// XXX
+#include <wchar.h>		/* ...to get mbstate_t, etc. */
 #endif
 
 #if 0

payloads/libpayload/include/stddef.h

@@ -3,6 +3,13 @@
 
 #include <arch/types.h>
 
+#ifndef __WCHAR_TYPE__
+#define __WCHAR_TYPE__ int
+#endif
+#ifndef __cplusplus
+typedef __WCHAR_TYPE__ wchar_t;
+#endif
+
 #ifndef __SIZE_TYPE__
 #define __SIZE_TYPE__ unsigned long
 #endif

payloads/libpayload/include/wchar.h

@@ -0,0 +1,11 @@
+#ifndef _WCHAR_H
+#define _WCHAR_H
+
+#include <stddef.h>
+
+#ifndef __WINT_TYPE__
+# define __WINT_TYPE__ unsigned int
+#endif
+typedef __WINT_TYPE__ wint_t;
+
+#endif