RFR(s): 8228580: DnsClient TCP socket timeout

[Florian Weimer]

* Milan Mimica:

> Continuing in a new thread with a RFR of my own:
> http://cr.openjdk.java.net/~mmimica/8228580/webrev.00/

I would add a comment why there's no explicit TCP connection timeout in
the code.  I assume you rely on the TCP stack having its own timeout,
right?  But I think it can be quite long under some circumstances.

The timeout will not be enforced properly if the clock jumps backwards.

Thanks,
Florian