s3:smbd: avoid invalid lock_order panic triggered by "CTDB_SRVID_RELEASE_IP"

s3:smbd: avoid invalid lock_order panic triggered by "CTDB_SRVID_RELEASE_IP"

If smbd_server_connection_terminate("CTDB_SRVID_RELEASE_IP") is triggered from
within ctdbd_migrate(), we got a smb_panic complaining about invalid
lock_order, as ctdbd_migrate is called from dbwrap_fetch_locked().

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10444
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Fri Feb 21 14:51:51 CET 2014 on sn-devel-104