macros that call pmap_count(). (from Jeremy).
Define pmap_resident_count(), pmap_wired_count() to call pmap_resident_pages(), pmap_wired_pages() respectively, so we can keep those statistics on lower-level structures instead of here.
Kill macros PMAP_ACTIVATE and PMAP_ACTIVATE (not used). Add macro _pmap_fault for use in trap.c