ike-sa-manager: Avoid deadlock due to race condition during shutdown

ike-sa-manager: Avoid deadlock due to race condition during shutdown

If an entry is added while we wait for a checked out SA in flush() (e.g.
due to an action performed by that SA), new entries might get inserted
before the one we wait for.  If that was the first entry in the row, we
didn't correctly update the table and the new entries were basically lost
by overwriting the first entry in the row.  As the SA count was still
increased but the new entries couldn't get enumerated, the daemon wasn't
terminated properly but was stuck in the loop in flush().