fenced: full check for member changes
    
    cman members are queried in response to a callback,
    and members sometimes leave and rejoin between queries
    (e.g. when they leave and rejoin before corosync
    detects they left.)
    
    This means that simply checking if a node is a member
    in consecutive queries sometimes misses events.  We
    need to compare the incarnation numbers of members
    from consecutive queries to avoid this.
    
    bz 663397
    
    Signed-off-by: David Teigland <teigland@redhat.com>