message: fix downloading admin realm
diff: #include "object_store.hpp"
  #include "results.hpp"
  #include "object_schema.hpp"
  -#include "util/event_loop_signal.hpp"
  +#include "event_loop_dispatcher.hpp"
  #include "sync/sync_config.hpp"
  #include "sync/sync_manager.hpp"
  @@ -56,7 +56,7 @@ AdminRealmListener::AdminRealmListener(std::string local_root, std::string serve
  void AdminRealmListener::start(std::function<void(std::vector<std::string>)> callback)
  {
  auto session = SyncManager::shared().get_session(m_config.path, *m_config.sync_config);
  - bool result = session->wait_for_download_completion([this, callback](std::error_code ec) {
  + EventLoopDispatcher<void(std::error_code)> download_callback([this, callback, session](std::error_code ec) {
  if (ec)
  throw std::system_error(ec);
  @@ -88,5 +88,6 @@ void AdminRealmListener::start(std::function<void(std::vector<std::string>)> cal
  }
  });
  });
  + bool result = session->wait_for_download_completion(std::move(download_callback));
  REALM_ASSERT_RELEASE(result);
  }
  