Add needed functions to glibc-compat for pkg

ports/glibc-compat/include/sys/unistd.h

 /*
  * Copyright (c) 2014 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef GLIBCEMU_SYS_UNISTD_H
 #define GLIBCEMU_SYS_UNISTD_H
 
 #include_next <sys/unistd.h>
 
 #include <sys/stat.h>
 #include <sys/types.h>
 
 /*
  * TODO(bradnelson): Consider adding sysconf (and this define) to nacl_io.
  * This would allow us to return more useful values.
  * For example nacl_io knows what this one should be.
  *
  * This sysconf parameter is unsupported by newlib, pick a bad value so that
  * we can still build when this is used, and instead hit a runtime error.
  * One port (tcl) has a fallback in this case to guess a reasonable value.
  */
 #define _SC_GETPW_R_SIZE_MAX (-1)
 #define _SC_GETGR_R_SIZE_MAX (-1)
 #define _SC_MONOTONIC_CLOCK (-1)
 #define _SC_OPEN_MAX (-1)
 #define _SC_CLK_TCK (-1)
+#define _SC_ARG_MAX (-1)
 
 /* TODO(bradnelson): Drop this once we've landed nacl_io pipe support. */
 extern int mknod(const char *pathname, mode_t mode, dev_t dev);
 extern int mkfifo(const char *pathname, mode_t mode);
 
+int readlinkat(int dirfd, const char *pathname,
+                      char *buf, size_t bufsiz);
+int unlinkat(int dirfd, const char *pathname, int flags);
+int faccessat(int dirfd, const char *pathname, int mode, int flags);
+int fchownat(int dirfd, const char *pathname,
+                    uid_t owner, gid_t group, int flags);
+int symlinkat(const char *oldpath, int newdirfd, const char *newpath);
+int linkat(int olddirfd, const char *oldpath,
+           int newdirfd, const char *newpath, int flags);
 
 #endif