Merge from vmc-playground branch:
Rename the pv_entry_t iterator from pv_list to pv_next.
Besides being more correct technically (as the name seems to suggest
this is a list while it is an iterator), it will also be needed by
vm_radix work to avoid a nameclash on macro expansions.

Sponsored by:	EMC / Isilon storage division
Reviewed by:	alc, jeff
Tested by:	flo, pho, jhb, davide
Fix callout expiring dynamic rules.

PR:		kern/175530
Submitted by:	Vladimir Spiridenkov <vs@gtn.ru>
MFC after:	2 weeks
Garbage collect HPFS bits which are now already completely disconnected
from the tree since few months (please note that the userland bits
were already disconnected since a long time, thus there is no need
to update the OLD* entries).

This is not targeted for MFC.