Run interrupt handlers in lifo order.

signal.go

@@ -28,7 +28,10 @@ func mainInterruptHandler() {
 		select {
 		case <-interruptChannel:
 			btcdLog.Infof("Received SIGINT (Ctrl+C).  Shutting down...")
-			for _, callback := range interruptCallbacks {
+			// run handlers in LIFO order.
+			for i  := range interruptCallbacks {
+				idx := len(interruptCallbacks) -1 -i
+				callback := interruptCallbacks[idx]
 				callback()
 			}