Update darkstat to 3.0.718.
per maintainer update request by PR pkg/49345.

v3.0.718 (25 January 2014)
- (SECURITY!) Don't chroot() by default.  The user must specify
  a --chroot dir for this to happen now.
- Bring back the "--base /path" functionality.
- Add explicit warning about graphs being blank if we can't get
  local IPs on an interface.
- Don't crash in timer_stop() if monotonic time stops or goes
  backwards.
- Lots of internal cleanups.
- Use time_t instead of "long" for time.  This is more correct
  and should fix darkstat on OpenBSD 5.5 on 32-bit systems.

(obache)