Use blocking lock when creating db2 KDB

In 1.11 we switched from non-blocking to blocking locks in the DB2
module, but we missed one call to krb5_lock_file() in ctx_create_db().
This non-blocking lock can cause krb5_db_promote() to fail if the
database is locked when we try to promote the DB, in turn causing
kdb5_util load to fail.  Correct this call to make krb5_db_promote()
more robust.

(cherry picked from commit 1868916dbb60a64b92da217257b4ed021262afd3)

https://github.com/krb5/krb5/commit/a288a808a0a550fa20ee8361a60f6de9578bdbf4
Author: Greg Hudson <ghudson@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: a288a808a0a550fa20ee8361a60f6de9578bdbf4
Branch: krb5-1.13
 src/plugins/kdb/db2/kdb_db2.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)