kernel - VM rework part 17 - Cleanup

kernel - VM rework part 17 - Cleanup

* Adjust kmapinfo and vmpageinfo in /usr/src/test/debug.
  Enhance the code to display more useful information.

* Get pmap_page_stats_*() working again.

* Change systat -vm's 'VM' reporting.  Replace VM-rss with PMAP and
  VMRSS.  Relabel VM-swp to SWAP and SWTOT.

  PMAP	- Amount of real memory faulted into user pmaps.

  VMRSS	- Sum of all process RSS's in thet system.  This is
	  the 'virtual' memory faulted into user pmaps and
	  includes shared pages.

  SWAP	- Amount of swap space currently in use.

  SWTOT	- Total amount of swap installed.

* Redocument vm_page.h.

* Remove dead code from pmap.c (some left over cruft from the
  days when pv_entry's were used for PTEs).