Introduce amqqueue.pending_slave_pids

include/rabbit.hrl

@@ -77,7 +77,8 @@
           gm_pids,                     %% transient
           decorators,                  %% transient, recalculated as above
           state,                       %% durable (have we crashed?)
-          policy_version}).
+          policy_version,
+          pending_slave_pids}).
 
 -record(exchange_serial, {name, next}).
 

src/rabbit_amqqueue.erl

@@ -303,7 +303,8 @@ declare(QueueName, Durable, AutoDelete, Args, Owner, Node) ->
                                       recoverable_slaves = [],
                                       gm_pids            = [],
                                       state              = live,
-                                      policy_version     = 0 })),
+                                      policy_version     = 0,
+                                      pending_slave_pids = []})),
 
     Node1 = case rabbit_queue_master_location_misc:get_location(Q)  of
               {ok, Node0}  -> Node0;