GENC should always export composite names

RFC 6680 requires that gss_export_name_composite begin the output
token with 04 02.  So we must produce a composite token even if the
name has no authdata, and be able to consume a composite token with no
authdata attributes.

[ghudson@mit.edu: expanded commit message]

https://github.com/krb5/krb5/commit/123ff4cb9bdd2e13aa6b636c98a7fc3f9ee06f85
Author: Luke Howard <lukeh@padl.com>
Committer: Greg Hudson <ghudson@mit.edu>
Commit: 123ff4cb9bdd2e13aa6b636c98a7fc3f9ee06f85
Branch: master
 src/lib/gssapi/krb5/import_name.c |    9 ++++++---
 src/lib/gssapi/krb5/naming_exts.c |   13 ++++++-------
 2 files changed, 12 insertions(+), 10 deletions(-)