[krbdev.mit.edu #3201] repair kdb locking

[Ken Raeburn via RT]

The kdb locking tests (lib/kadm5/unit-test/api.1/lock.exp) fail
after the DAL merge.

I'm going to temporarily disable the test, but it must be re-enabled
and the locking problems fixed before the 1.5 release.  (Unless
there's a good reason for the change in behavior, in which case the
test case should be updated to reflect the new locking strategy.)

Ken