Fix decoding of mkey kvno in mkey_aux tl-data

krb5_dbe_lookup_mkey_aux was decoding a 16-bit value directly into an
int, resulting in the wrong value on big-endian platforms.  The
consequences are mostly invisible because we ignore this field and try
all mkey_aux nodes in krb5_def_fetch_mkey_list.

(cherry picked from commit 64ec2941af1561ef06e7e885b2ffb65a675516ce)

https://github.com/krb5/krb5/commit/79e91cfc49a8583ff0541dd0377b6926db6f08c0
Author: Greg Hudson <ghudson@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 79e91cfc49a8583ff0541dd0377b6926db6f08c0
Branch: krb5-1.12
 src/lib/kdb/kdb5.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)