vkernel64 - Cleanup, unbreak 32 bit

vkernel64 - Cleanup, unbreak 32 bit

* Remove stdio cruft from init_main.c

* Change vpte_t from 64-bits to u_long, so it will be 32 bits
  on 32 bit machines and 64 bits on 64 bit machines.  32 bit
  machines can't handle the address space breakdown or issue
  atomic ops on 64 bit quantities.

  Adjust various defines in sys/vkernel.h to accomodate both
  cases.

* Adjust atomic ops used by vm/vm_fault.c for virtual page
  table access (int -> long).

* Adjust atomic ops and types used by the 32 bit
  platform/vkernel code, primarily (int -> long) and
  also some vm_offset_t's which are really vm_paddr_t's
  or vpte_t's.

* Adjust src/test/vkernel/Makefile to run properly on
  a 32 or 64 bit system.