kernel - Replace global vmobj_token with vmobj_tokens[] array

kernel - Replace global vmobj_token with vmobj_tokens[] array

* Remove one of the two remaining major bottlenecks in the system, the
  global vmobj_token which is used to manage access to the vm_object_list.
  All VM object creation and deletion would get thrown into this list.

* Replace it with an array of 64 tokens and an array of 64 lists.
  vmobj_token[] and vm_object_lists[].  Use a simple right-shift
  hash code to index the array.

* This reduces contention by a factor of 64 or so which makes a big
  difference on multi-chip cpu systems.  It won't be as noticable on
  single-chip (e.g. 4-core/8-thread) systems.

* Rip-out some of the linux vmstats compat functions which were iterating
  the object list and replace with the pcpu accumulator scan that was
  recently implemented for dragonfly vmstats.

* TODO: proc_token.