Also update log message and description

This is part of the cleanup.  as we removed the corresponding
interface at DNSService, no one now uses these constructors.

the rest of code actually didn't need this directive, so the removal shouldn't
do any harm anyway.

It compiles, but has some problems in tests.

Actually, the SyncUDPSocket is currently a copy of the UDPSocket. It
needs to get stripped little bit.

needed for some systems that have system headers that don't include headers that
define what they need.

Catch on the closing bracket, include little bit more in the try.

Just consistency and performance.

* Use the address family instead of v6 boolean.
* Check it by exception.
* Documentation.

(based on the seeming intent), indentation.

One compiler had a problem with the unqualifier data type
"error_code".  This has been changed to "asio::error_code".

No need to create an opened socket and close it right away.

The dns_service is not tested, so the tests are not added. It is simple
anyway.

[trac678] refactor the stop interface for udp and tcp server and related unittest to dns_server_unitttest

okayed via jabber

The asio wraps them, so we can be portable.

skipping review.

Like when the socket is closed. Trying to accept more connections on
such socket lead to busy loop.

These should probably really be done by asio.hpp

IOFetch is a general upstream "fetch" class that should be able to
operate over TCP or UDP.  Related changes have been made in the
associated classes.  So far, only the unit tests for a UDP fetch
have been made (and passed).

It only stores the final result, and only looks into the cache at the start of a resolve() call right now, but it appears to work

forgot an EXTRA_DIST for the distcheck, and sunstudio needs unistd to be included before asio.hpp