message: Fix return value of RemoteServer::DriverName()
diff: @@ -1646,7 +1646,8 @@ public:
  rdcstr DriverName()
  {
  if(!Connected())
  - return 0;
  + return "";
  +
  {
  WRITE_DATA_SCOPE();
  SCOPED_SERIALISE_CHUNK(eRemoteServer_GetDriverName);
  