Adding bsdiff to the base system

[Colin Percival]

  I'd like to add bsdiff/bspatch into the base system.  I
initially wrote these as part of FreeBSD Update, but I'm now
also using them in portsnap, and bspatch has been part of the
OS X base system for most of the past year as a result of
being used by their patches.
  My reason for wanting to add this is that portsnap is next
on my hit list, and I obviously need to get this done first.

  Any objections?

Colin Percival