Start bringing in Ricardo's spl-00-rhel4-compat.patch, a few chunks

Start bringing in Ricardo's spl-00-rhel4-compat.patch, a few chunks
at a time as I audit it.  This chunk finishes moving the SPL entirely
off the linux slab on to the SPL implementation.  It differs slightly
from the proposed version in that the spl continues to export to
all the Solaris types and functions.  These do conflict with the
Linux slab so a module usings these interfaces must not include the
SPL slab if they also intend to use the linux slab.  Or they must
explcitly #undef the macros which remap the functioin to their
spl_* equivilants.

A nice side of effect of dropping the entire linux slab is we
don't need to autoconf checks anymore.  They kept messing with
the slab API endlessly!

git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@148 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c