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/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