It may be desirable to have custom link<> properties that do more
than just store an object. Even the addition of a "check"
function is not enough if setting the link has side effects
or if a non-standard reference counting is preferrable.
Avoid the assumption that the opaque field of a link<> is a
LinkProperty struct, by adding a generic "resolve" callback
to ObjectProperty. This fixes aliases of link properties.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
64607d0881