Add support to delete all objects attached to the root namespace node.

This fix deletes any and all objects that have been attached to the
root node (via AcpiAttachData). Reported by Tomasz Nowicki.
ACPICA BZ 1026.
AcpiExec: Add support to test attach/delete root node objects.

This change attaches two objects to the root node to test both
the attach and the actual object deletion upon ACPICA termination.