EDNS - edns-udp-size and max-udp-size

[Evan Hunt]

> 	The code just looks at the number of timeouts not at what
> 	size was sent in the initial query.  triededns512() records
> 	when the DNS_FETCHOPT_EDNS512 has been set not when the
> 	initial query advertised a receive buffer of 512 bytes.

But, if the initial query uses a receive buffer of 512 bytes or less,
can't we just set DNS_FETCHOPT_EDNS512 straight off and save a step?

                                        eh