2014-01-06  Sebastian Huber  <sebastian.huber@embedded-brains.de>

        * libc/include/sys/_default_fcntl.h (AT_FDCWD): Define according
        to POSIX.
        (AT_EACCESS): Likewise.
        (AT_SYMLINK_NOFOLLOW): Likewise.
        (AT_SYMLINK_FOLLOW): Likewise.
        (AT_REMOVEDIR): Likewise.
        (openat): Declare according to POSIX.
        * libc/include/stdio.h (renameat): Likewise.
        * libc/include/sys/stat.h (fchmodat): Likewise.
        (fstatat): Likewise.
        (mkdirat): Likewise.
        (mkfifoat): Likewise.
        (mknodat): Likewise.
        (utimensat): Likewise.
        (futimens): Likewise.
        * libc/include/sys/unistd.h (faccessat): Likewise.
        (fchownat): Likewise.
        (linkat): Likewise.
        (readlinkat): Likewise.
        (symlinkat): Likewise.
        (unlinkat): Likewise.