Changes

osmo-hlr: Force log stderr blocking-io in --db-check mode

When --db-check is used, osmo-hlr actually becomes a synchronous
non-interactive program instead of a daemon.
In that case, we want to use blocking-io since it doesn't use the event
loop, so we want to flush all logging synchronously before exiting.

Usually the user will pass the same osmo-hlr.cfg when running with
--db-check, which means most probably won't be using blocking-io (as
expected when osmo-hlr runs in daemon mode).
Since --db-check converts osmo-hlr to a cmdline which exits after checks
are done, we actually want to force blocking-io in that case, so that
all content is written to stderr before finishing the process.

Change-Id: If5e505383086cc55d724c0d6891756c8d94fa267