* get_creds.c (krb5_get_credentials_core): new function. Common part of

* get_creds.c (krb5_get_credentials_core): new function. Common part of
krb5_get_credentials and krb5_get_credentials_validate.  Some formerly local
variables are now arguments.
(krb5_get_credentials): same as before, but calls _core to do some of the work.
(krb5_get_credentials_validate): uses krb5_get_cred_from_kdc_validate and only
stores the returned credential in the cache, instead of storing all of them.

* gc_frm_kdc.c (krb5_get_cred_from_kdc_opt): new function. Same body as
krb5_get_cred_from_kdc, but takes one new argument, kdcopts, and combines it
with the other kdc options when calling krb5_get_cred_via_tkt. This is static
and only called by
(krb5_get_cred_from_kdc): a wrapper that provides the same function it did
before, and
(krb5_get_cred_from_kdc_validate): a wrapper that passes KDC_OPT_VALIDATE, so
that kinit can use it.
We'll probably need another one for renewing tickets as well.

* rd_req_dec.c (krb5_rd_req_decoded_opt): new function. Same body as
krb5_rd_req_decoded, but takes one new argument, check_valid_flag, to determine
whether or not to check if the "invalid flag" is set in the ticket. Also made
static, so that it is only called via:
(krb5_rd_req_decoded): wrapper for krb5_rd_req_decoded_opt that specifies the
"invalid flag" gets checked, and
(krb5_rd_req_decoded_anyflag): wrapper for krb5_rd_req_decoded_opt that
specifies that the "invalid flag" doesn't get checked. (This version is only
called from kdc_util.c:kdc_process_tgs_req.)

* str_conv.c (krb5_string_to_timestamp): double check that strptime at least
parsed *some* of the string, avoid degenerate cases from GNU libc strptime.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@7890 dc483132-0cff-0310-8789-dd5450dbe970