The corosync message "A processor joined or left the membership" is
vague and unhelpful. People have to look for the following quorum
message and try to deduce which nodes have joined or left from that
and past membership messages, even though the routine printing the
message already has this information to hand.

This patch fixes that message so that it prints the nodeids of the nodes
that have joined/left the cluster.

Signed-Off-By: Christine Caulfield <ccaulfie@redhat.com>
Reviewed-By: Jan Friesse <jfriesse@redhat.com>