selftest: Use 'logging' parameter instead of 'syslog'

'syslog' has been deprecated, so use the new 'logging' parameter
instead.

Signed-off-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>

Autobuild-User(master): Michael Adam <obnox@samba.org>
Autobuild-Date(master): Fri Mar 27 06:38:32 CET 2015 on sn-devel-104
