8.0-BETA3 reproducible panic under load

[Li, Qing]

>
> Not sure if this is what you hit or not.  I once saw something
similar.
> The call to LLE_FREE() in ip_output doesn't expect NULL.  Adding
>    if (ro->ro_lle != NULL)
> just before the call to LLE_FREE() may fix your crashes.
> 

Actually, LLE_FREE() should not be called at all here because the 
"if (!nortfree)" block test applies to route entries that are not 
from the flow-table.  And if the route entry is not from the
flow-table, then the rt_lle field is invalid.

I will commit the fix.

Thanks,

-- Qing