- Show address string from proper buffer in case of connection failure.

- Try next address when inet_ntop() fails.

and the traditional source header

Reinstate IPV6 build variable that got removed.

Failed to commit this file changes along with the others.

warning C4146: unary minus operator applied to unsigned type, result still unsigned

Ensure that spurious results from system's getaddrinfo() ares not propagated
by Curl_getaddrinfo_ex() into the library.

Also ensure that the ai_addrlen member of Curl_getaddrinfo_ex()'s output linked
list of Curl_addrinfo structures has appropriate family-specific address size.

... not the proxy port.  It makes no difference unless a proxy is used.

Winsock builds clobber some errno.h defines in setup_once.

This showed a problem when running the test out-of-tree, so
an include path is now being added to pick up the generated
curlbuild.h file.

On Windows, translate WSAGetLastError() to errno values as GNU
TLS does it internally, too. This is necessary because send() and
recv() on Windows don't set errno when they fail but GNU TLS
expects a proper errno value.

Bug: http://curl.haxx.se/bug/view.cgi?id=3110991