* dirmngr/workqueue.c: New.
* dirmngr/Makefile.am (dirmngr_SOURCES): Add new file.
* dirmngr/server.c (server_local_s): New field session_id.
(cmd_wkd_get): Add a task.
(task_check_wkd_support): New stub function.
(cmd_getinfo): New sub-commands "session_id" and "workqueue".
(start_command_handler): Add arg session_id and store it in
SERVER_LOCAL.
(dirmngr_status_helpf): New.
* dirmngr/dirmngr.h (wqtask_t): New type.
* dirmngr/dirmngr.c (main): Pass 0 as session_id to
start_command_handler.
(start_connection_thread): Introduce a session_id and pass it to
start_command_handler.  Run post session tasks.
(housekeeping_thread): Run global workqueue tasks.