messaging3: Directly refer to messaging_dgm in messages.c
This removes the messaging_backend abstraction layer from messages_dgm.c. That
layer was introduced for ctdb and is still used there. But as the messaging_dgm
interface is very slim anyway, I don't think directly calling it is too bad.
Why this commit? It is another step towards making messages_dgm
independent of messages.[ch], thus it might become usable in other
contexts like ctdb and source4
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>