Improve algorithm for deciding whether to loop through all process pages or look them up individually in pmap_remove() and apply the same logic in the other ranged operation (pmap_protect). This speeds up make installworld by a factor of 2 on powerpc64.
Improve algorithm for deciding whether to loop through all process pages
or look them up individually in pmap_remove() and apply the same logic
in the other ranged operation (pmap_protect). This speeds up make
installworld by a factor of 2 on powerpc64.

MFC after:	1 week

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