s3:debug: enable logging for early startup failures

s3:debug: enable logging for early startup failures

Commit c89a33a07a 'debug: Use backends instead of explicitly logging to
syslog or file' introduced a regression where early startup failures (e.g.
unable to connect to CTDB) are no longer logged because the debug subsystem
is not yet fully initialized. Enable logging again with reasonable defaults
when reopen_logs() is called and the parameter file is not yet parsed.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13904

Signed-off-by: Ralph Wuerthner <ralph.wuerthner@de.ibm.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Christof Schmitt <cs@samba.org>
Autobuild-User(master): Christof Schmitt <cs@samba.org>
Autobuild-Date(master): Thu Apr 18 22:21:15 UTC 2019 on sn-devel-144