[FAB-14688] Check inner, not outer block msg

The gossip code that handles pull block data updates
has an optimization that first performs a simulation
of adding an inner block message to the message store,
and only if the simulation is successful  -
it then verifies the message.

The problem is that the simulation is done against the outer
message, and thus the optimization does not occur.

This change set fixes this.

Change-Id: I71c94e9b1cad2bfa6e9cfce700d8bd3209e9b5e7
Signed-off-by: yacovm <yacovm@il.ibm.com>

gossip/gossip/channel/channel.go

@@ -592,8 +592,8 @@ func (gc *gossipChannel) HandleMessage(msg proto.ReceivedMessage) {
 					return
 				}
 				// Would this block go into the message store if it was verified?
-				if !gc.blockMsgStore.CheckValid(msg.GetGossipMessage()) {
-					return
+				if !gc.blockMsgStore.CheckValid(gMsg) {
+					continue
 				}
 				if !gc.verifyBlock(gMsg.GossipMessage, msg.GetConnectionInfo().ID) {
 					return