[2205] create DataSrcClientsMgr in auth's main() just to confirm it starts/ends

it currently does nothing user-visible.

src/bin/auth/main.cc

@@ -36,6 +36,8 @@
 #include <auth/auth_srv.h>
 #include <auth/auth_log.h>
 #include <auth/datasrc_config.h>
+#include <auth/datasrc_clients_mgr.h>
+
 #include <asiodns/asiodns.h>
 #include <asiolink/asiolink.h>
 #include <log/logger_support.h>
@@ -230,6 +232,10 @@ main(int argc, char* argv[]) {
         isc::server_common::initKeyring(*config_session);
         auth_server->setTSIGKeyRing(&isc::server_common::keyring);
 
+        // Instantiate the data source clients manager.  At the moment
+        // just so we actually create it in system tests.
+        DataSrcClientsMgr datasrc_clients_mgr;
+
         // Start the data source configuration.  We pass first_time and
         // config_session for the hack described in datasrcConfigHandler.
         bool first_time = true;