Clearing a page table entry's accessed bit and setting the page's
PG_REFERENCED flag in pmap_protect() can't really be justified, so
don't do it.
Additionally, two changes that make this pmap behave like the others do:
Change pmap_protect() such that it calls vm_page_dirty() only if the
page is managed.
Change pmap_remove_write() such that it doesn't clear a page table
entry's accessed bit.
c7a0df65b1