Kernel: Use symbolic constants for file modes

This fixes a bug where the mode of a FIFO was reported as 001000 instead
of 0010000 (you see the difference? me nethier), and hopefully doesn't
introduce new bugs. I've left 0777 and similar in a few places, because
that is *more* readable than its symbolic version.

Kernel/UnixTypes.h

@@ -108,6 +108,28 @@
 #define FUTEX_WAIT 1
 #define FUTEX_WAKE 2
 
+#define S_IFMT 0170000
+#define S_IFDIR 0040000
+#define S_IFCHR 0020000
+#define S_IFBLK 0060000
+#define S_IFREG 0100000
+#define S_IFIFO 0010000
+#define S_IFLNK 0120000
+#define S_IFSOCK 0140000
+
+#define S_ISUID 04000
+#define S_ISGID 02000
+#define S_ISVTX 01000
+#define S_IRUSR 0400
+#define S_IWUSR 0200
+#define S_IXUSR 0100
+#define S_IRGRP 0040
+#define S_IWGRP 0020
+#define S_IXGRP 0010
+#define S_IROTH 0004
+#define S_IWOTH 0002
+#define S_IXOTH 0001
+
 /* c_cc characters */
 #define VINTR 0
 #define VQUIT 1