6357424 zfs io test lead to usage of low 16M memory

[kit.c...@sun.com]

Author: kchow
Repository: /hg/onnv/onnv-gate
Revision: 1d781594403dee533966905d622007efb8f6ba17
Log message:
6357424 zfs io test lead to usage of low 16M  memory
6372227 physmax4g under skanky #ifndef in page_create_get_something()

Files:
        update: usr/src/uts/common/vm/vm_page.c
        update: usr/src/uts/common/vm/vm_pagelist.c
        update: usr/src/uts/i86pc/vm/vm_dep.h
        update: usr/src/uts/i86pc/vm/vm_machdep.c
        update: usr/src/uts/sun4/vm/vm_dep.h