Use blocking locks for policy DB

In the db2 kdb module, use blocking locks for the policy DB as well as
the principal DB.

https://github.com/krb5/krb5/commit/e03a59074017dde6e0c524efcba9476aec064d17
Author: Greg Hudson <ghudson@mit.edu>
Commit: e03a59074017dde6e0c524efcba9476aec064d17
Branch: master
 src/plugins/kdb/db2/adb_openclose.c |   25 ++++++-------------------
 1 files changed, 6 insertions(+), 19 deletions(-)