A reply to a recovery message will often be received after the relevant
recovery sequence has aborted and the next recovery sequence has begun.
We need to ignore replies to these old messages from the previous
recovery.  There's already a way to do this for synchronous recovery
requests using the rc_id number, but not for async.

Each recovery sequence already has a locally unique sequence number
associated with it.  This patch adds a field to the rcom (recovery
message) structure where this recovery sequence number can be placed,
rc_seq.  When a node sends a reply to a recovery request, it copies the
rc_seq number it received into rc_seq_reply.  When the first node receives
the reply to its recovery message, it will check whether rc_seq_reply
matches the current recovery sequence number, ls_recover_seq, and if not
then it ignores the old reply.

An old, inadequate approach to filtering out old replies (checking if the
current stage of recovery has moved back to the start) has been removed
from two spots.

The protocol version number is changed to reflect the different rcom
structures.
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>