eventscript: don't make ourselves healthy if we're under ban_count

eventscript: don't make ourselves healthy if we're under ban_count

If we've timed out, but we've not timed out more than
ctdb->tunable.script_ban_count, we pretend we haven't.

There's a logic bug in the way this is done: if we were unhealthy before,
this would set us to "healthy" again (status == 0).  I don't think this
would happen in real life, but it's a little surprising.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>