9696 add /etc/system.d support
Portions contributed by: Andy Fiddaman <andy@omniosce.org>
Reviewed by: Hans Rosenfeld <hans.rosenfeld@joyent.com>
Reviewed by: Peter Tribble <peter.tribble@gmail.com>
Reviewed by: C Fraire <cfraire@me.com>
Reviewed by: Toomas Soome <tsoome@me.com>

*** 14,23 ****
--- 14,24 ----
  etc/name_to_major
  etc/name_to_sysnum
  etc/path_to_inst
  etc/rtc_config
  etc/system
+ etc/system.d
  etc/hostid
  kernel
  platform/i86hvm/kernel
  platform/i86pc/kernel
  platform/i86xpv/kernel