MFC r233290, r235598, r235973, r236045, r236240, r236291, r236378

MFC r233290, r235598, r235973, r236045, r236240, r236291, r236378
  Change pv_entry_count to a long on amd64.

  Rename pmap_collect() to pmap_pv_reclaim() and rewrite it such that it
  no longer uses the active and inactive paging queues.

  Eliminate some purely stylistic differences among the amd64, i386
  native, and i386 xen PV entry allocators.

  Eliminate code duplication in free_pv_entry() and pmap_remove_pages()
  by introducing free_pv_chunk().

git-svn-id: svn://svn.freebsd.org/base/stable/9@237950 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f