Update code for checking the reference count and performing the final

Update code for checking the reference count and performing the final
delete of objects.  Also revert our temporary workaround in dsmthdat.c
that always copied objects.  This is the correct fix for errors
evaluating _BST (and GBST) on IBM Thinkpads where an argument (Arg3)
was returned to the caller and the object was freed while still in use.
This will be in a future ACPI-CA dist.

Thanks to:	kochi@netbsd.org, shaohua.li@intel.com