[master] Patch the failover code to avoid deadlocks

Patch for 36810 & 20352
This coves several related problems
1) When the primary is in conflict done it allows the secondary to
transition around resolution interrupted and potentical conflict previously
the primary would die on an illegal state.

2) It allows the servers to restart a bind update request.  Previously if
one of the servers sent an udpate request and there died (or had the communications
interrupted) in some states the first server wouldn't retransmit a new
update request and the other server wouldn't send any bind updates. This
was noticed in potential conflict.

3) Updated the state transitions to move the leases on the ack queue
back to the update queue in case of conflict-done as we might need to
retransmit them all.

4) Updated a transition from startup to potentical conflict instead
of resolution interrupted when the servers reconnect during the startup
phase in order to avoid a diffferent dead lock.

RELNOTES

@@ -137,6 +137,15 @@ by Eric Young (eay@cryptsoft.com).
   the patch upon which the fix is based.
   [ISC-Bugs #32222]
 
+- In the failover code, handle the case of communications being interrupted
+  when the servers are dealing with POTENTIAL-CONFLICT.  This patch allows
+  the primary to accept the secondary moving from POTENTIAL-CONFLICT to
+  RESOLUTION-INTERRUPTED as well as handling the bind update process better.
+  In addition the code to resend update or update all requests has been
+  modified to send requests more often.
+  [ISC-Bugs #36810]
+  [ISC-Bugs #20352]
+
 			Changes since 4.3.1b1
 
 - Modify the linux and openwrt dhclient scripts to process information