Fix build with newer newlib

pk/elf.c

@@ -1,14 +1,14 @@
 // See LICENSE for license details.
 
-#include "mmap.h"
 #include "pk.h"
 #include "mtrap.h"
 #include "boot.h"
 #include "bits.h"
+#include "elf.h"
 #include <sys/stat.h>
 #include <fcntl.h>
-#include <elf.h>
 #include <string.h>
+#include "mmap.h"
 
 /**
  * The protection flags are in the p_flags section of the program header.

pk/syscall.h

@@ -68,6 +68,7 @@
 #define ERR_PTR(x) ((void*)(long)(x))
 #define PTR_ERR(x) ((long)(x))
 
+#undef AT_FDCWD
 #define AT_FDCWD -100
 
 long do_syscall(long a0, long a1, long a2, long a3, long a4, long a5, unsigned long n);