kernel - VM rework part 18 - Cleanup

kernel - VM rework part 18 - Cleanup

* Significantly reduce the zone limit for pvzone (for pmap
  pv_entry structures).  pv_entry's are no longer allocated
  on a per-page basis so the limit can be made much smaller.

  This also has the effect of reducing the per-cpu cache limit
  which ultimately stabilizes wired memory use for the zone.

* Also reduce the generic pre-cpu cache limit for zones.
  This only really effects the pvzone.

* Make pvzone, mapentzone, and swap_zone __read_mostly.

* Enhance vmstat -z, report current structural use and actual
  total memory use.

* Also cleanup the copyright statement for vm/vm_zone.c.  John Dyson's
  original copyright was slightly different than the BSD copyright and
  stipulated no changes, so separate out the DragonFly addendum.