gpg: New option --with-key-origin.
* g10/getkey.c (parse_key_origin): Factor list out as ... (key_origin_list): new struct. (key_origin_string): New. * g10/gpg.c (oWithKeyOrigin): New const. (opts): New option --with-key-origin. (main): Implement option. * g10/options.h (struct opt): New flag with_key_origin. * g10/keylist.c (list_keyblock_print): Print key origin info. (list_keyblock_colon): Ditto.