[Reproducer] Assert on unexpected packet

I'm not able to reproduce the reproducer flakiness we're seeing on
GreenDragon. I want to add this assert to find out if the GDB remote
packets are somehow getting out of sync when this happens.

llvm-svn: 364852

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationReplayServer.cpp

@@ -142,6 +142,7 @@ GDBRemoteCommunicationReplayServer::GetPacketAndSendResponse(
                  entry.packet.data);
         LLDB_LOG(log, "GDBRemoteCommunicationReplayServer actual packet: '{0}'",
                  packet.GetStringRef());
+        assert(false && "Encountered unexpected packet during replay");
         return PacketResult::ErrorSendFailed;
       }