dirmngr: Implement command KS_DEL for ldap servers.
* dirmngr/server.c (cmd_ks_del): New. (percentplus_line_to_strlist): New. * dirmngr/ks-action.c (ks_action_del): New. * dirmngr/ks-engine-ldap.c (ks_ldap_del): New.
Backported-from-master: 9d356a172e7cc492707a6466d30ede8eb0dcf92d
- GnuPG-bug-id: T5447