dirmngr: Add basic libdns support
* dirmngr/dns.c: New file. * dirmngr/dns.h: New file. * dirmngr/Makefile.am (dirmngr_SOURCES): Add new files. * dirmngr/dns-stuff.c: Include dns.h.xxx use libdns (libdns): New global var for the libdns state. (libdns_error_to_gpg_error): New. (libdns_init): New. (resolve_name_libdns): New. (get_dns_cert_libdns): New stub. (getsrv_libdns): New stub. (get_dns_cname_libdns): New stub.
- Signed-off-by: Justus Winter <justus@g10code.com>