* keylist.c (list_cert_colon): New arg HAVE_SECRET, print "crs"
when we know that the secret key is available.
(gpgsm_list_keys): New arg MODE, check whether a secret key is
available. Changed all callers.
* gpgsm.c (main): New command --list-secret-keys.
* server.c (cmd_listsecretkeys): New.
(cmd_listkeys): Return secret keys with "crs" record.