- Remove hash functionality from slab in favor of direct lookups

- Remove hash functionality from slab in favor of direct lookups
  based of the spl_kmem_obj_t tacked on the end of each object.
  This actually isn't so back because we are now allocing large
  chunks for the slab and partitioning it ourselves.  So there's
  not a ton of wasted space.  We may suffer a performance hit
  however due to alignment issues.

- Remove remaining depenancies on the linux slab implementation.
  We're standing on our own now for better or worse.

- Rework slabs to be either kmem or vmem based.  If neither
  KMC_VMEM of KMC_KMEM are specified we make a decent guess
  about what will work best for their based on the object
  size.  Additionally we provide a kmem_virt() function caller
  can use to see if they have a virtual or physical address.

- Minor fixups in the test suite.

git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@141 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c