Rewrite asn1_get_tag interface to use a structure pointer rather than several

Rewrite asn1_get_tag interface to use a structure pointer rather than several
pointer variables for the returned data.  Use the structure in the caller when
straightforward; in cases where macros use different but overlapping sets of
automatic scalar variables in one file, copy the values out of the structures
for now, until they can be analyzed more carefully.

* asn1_get.c (asn1_get_tag): Deleted.
(asn1_get_tag_2): Renamed from asn1_get_tag_indef, now uses a pointer to
taginfo rather than a bunch of pointer args.
(asn1_get_id, asn1_get_length): Folded into asn1_get_tag_2.
(asn1_get_sequence): Call asn1_get_tag_2.
* asn1_get.h (taginfo): New structure.
(asn1_get_tag_indef, asn1_get_tag, asn1_get_id, asn1_get_length): Declarations
deleted.
(asn1_get_tag_2): Declare.
* asn1_decode.c (setup): Declare only a taginfo variable.
(asn1class, construction, tagnum, length): New macros.
(tag): Call asn1_get_tag_2.
* asn1_k_decode.c (next_tag, get_eoc, apptag, end_sequence_of,
end_sequence_of_no_tagvars, asn1_decode_krb5_flags): Call asn1_get_tag_2; if no
error, copy out values into scalar variables.
(asn1_decode_ticket): Call asn1_get_tag_2.
* asn1buf.c (asn1buf_skiptail): Call asn1_get_tag_2.
* krb5_decode.c (check_apptag, next_tag, get_eoc): Call asn1_get_tag_2; if no
error, copy out values into scalar variables.
(decode_krb5_enc_kdc_rep_part): Call asn1_get_tag_2.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@15274 dc483132-0cff-0310-8789-dd5450dbe970