dirmngr: Add command "GETINFO stats".
* dirmngr/server.c (cmd_getinfo): New sub-command "stats". (dirmngr_status_helpf): Allow for a CTRL of NULL. * dirmngr/certcache.c (cert_cache_print_stats): Add arg ctrl and use dirmngr_status_helpf. Adjust all callers. * dirmngr/domaininfo.c (domaininfo_print_stats): Ditto. * sm/certchain.c (ask_marktrusted): Flush stdout before printing the fingerprint.