especially useful now that libc's open() always calls openat(). While here,
fix a few other things:
- Decode the mode argument passed to access(), eaccess(), and faccessat().
- Decode the atfd paramete to pretty-print AT_FDCWD.
- Decode the special AT_* flags used with some of the *at() system calls.
- Decode arguments for fchmod(), lchmod(), fchown(), lchown(), eaccess(),
and futimens().
- Decode both of the timeval structures passed to futimes() instead of just
the first one.
7d89732757