roken: Define S_IRWXU and friends on Windows

POSIX mkdir (unlike the Windows version) takes a 'mode_t' parameter.
Provide definitions for the mode_t constants.

Change-Id: Ie57e746aa3e579e28f93064ab430f1128508cc84

lib/roken/roken.h.in

@@ -357,6 +357,21 @@ rk_vsnprintf (char *str, size_t sz, const char *format, va_list args);
  S_ISBLK(m)
 */
 
+/* The following symbolic constants are provided for rk_mkdir mode */
+
+#define S_IRWXU 00700 /* user (file owner) has read, write and execute permission */
+#define S_IRUSR 00400 /* user has read permission */
+#define S_IWUSR 00200 /* user has write permission */
+#define S_IXUSR 00100 /* user has execute permission */
+#define S_IRWXG 00070 /* group has read, write and execute permission */
+#define S_IRGRP 00040 /* group has read permission */
+#define S_IWGRP 00020 /* group has write permission */
+#define S_IXGRP 00010 /* group has execute permission */
+#define S_IRWXO 00007 /* others have read, write and execute permission */
+#define S_IROTH 00004 /* others have read permission */
+#define S_IWOTH 00002 /* others have write permission */
+#define S_IXOTH 00001 /* others have execute permission */
+
 #if !defined(ROKEN_NO_DEFINE_ALLOCATORS)
 /* Ensure that a common memory allocator is used by all */
 #define calloc  rk_calloc