WIP: use SPL facilities to determine how much RAM to free.
WIP: Add missing cache reclaim function from illumos.
WIP: Have ARC provide a stronger reaction to downward changes in
zfs.arc_max. Dissapointing arc_used appears small at all times
so this does not really work.
WIP: cleanups, remove incompatible kmem flags, replace with "correct" alternates.
WIP: Disabled compilation of AVL in ZFS, use the SPL one instead.
WIP: convert linux vmem_alloc/free calls to kmem_ equivs. vmem on linux has a completely different meaning than vmem on illumos.
WIP: avoid participating in memory defragmentation for now - some code is currently #ifdefed out.
ZFS really needs the memory in use test in arc_reclaim_needed, otherwise
we basically get runaway memory allocation.