[Libvirt-cim] [PATCH 0 of 2] Move two classes to cu_compare_ref()

[Dan Smith]

The first patch removes the internal reference key checking from VSMS
in favor of the libcmpiutil generic one.  The second makes ComputerSystem
do similar checking.  If this looks good to people, we'll want to do this
for (probably) all of the instance providers.