Function dtrace_dof_slurp

* The dof_hdr_t passed to dtrace_dof_slurp() should be a partially validated * header: it should be at the front of a memory region that is at least * sizeof (dof_hdr_t) in size -- and then at least dof_hdr.dofh_loadsz in * size. It need not be validated in any other way. */