* src/cms.h (struct ksba_cms_s): Remove struct data which was not
used.  Add struct authdata.
* src/cms.asn (AuthEnvelopedData): New.
(id-authEnvelopedData): New.
* src/ksba.h.in (ksba_content_type_t): Add KSBA_CT_AUTHENVELOPED_DATA.
* src/cms.c (content_handlers): Ditto.
(ksba_cms_release): Free the new fields.
(ksba_cms_get_message_digest): Hack to return authtag.
(ct_parse_signed_data): Remove useless condition which was always true.
* src/cms-parser.c (parse_encrypted_content_info): Add arg
r_algo_parmtype.
(_ksba_cms_parse_enveloped_data_part_1): Detect GCM with AES and parse
the parameters.
(_ksba_cms_parse_enveloped_data_part_2): Parse the MAC part and store
it for retrieval by ksba_cms_get_message_digest.
* tests/t-cms-parser.c (one_file): Handle authdata.