Using CHANNEL_PRINTS to transfer printbuffers to stdout is now working.

luprex/cpp/core/lpxclient.cpp

@@ -276,6 +276,7 @@ public:
                 if (print_channeler_.channel(world_->get_printbuffer(actor_id_), retpk)) {
                     send_invocation(print_channeler_.invocation(actor_id_));
                 }
+                set_have_prints(false);
                 break;
             }
             default: {
@@ -313,6 +314,8 @@ public:
                 world_to_asynchronous();
             }
         }
+
+        set_have_prints(print_channeler_.have_prints(world_->get_printbuffer(actor_id_)));
     }
 };