Kernel: Fix directory permissions

We did not care about X bit in directories and instead used only the
R bit for search/read.

libc/include/sys/syscall.h

@@ -52,6 +52,8 @@ __BEGIN_DECLS
 #define SYS_SET_PGID 45
 #define SYS_FCNTL 46
 #define SYS_NANOSLEEP 47
+#define SYS_FSTATAT 48
+#define SYS_STAT 49 // stat/lstat
 
 __END_DECLS