(http://curl.haxx.se/bug/view.cgi?id=1481217), with follow-ups by Michele Bini
and David Byron. libcurl previously wrongly used GetLastError() on windows to
get error details after socket-related function calls, when it really should
use WSAGetLastError() instead.

When changing to this, the former function Curl_ourerrno() is now instead
called Curl_sockerrno() as it is necessary to only use it to get errno from
socket-related functions as otherwise it won't work as intended on Windows.

(http://curl.haxx.se/bug/view.cgi?id=1480821) He found and identified a
problem with how libcurl dealt with GnuTLS and a case where gnutls returned
GNUTLS_E_AGAIN indicating it would block. It would then return an unexpected
return code, making Curl_ssl_send() confuse the upper layer - causing random
28 bytes trash data to get inserted in the transfered stream.

The proper fix was to make the Curl_gtls_send() function return the proper
return codes that the callers would expect. The Curl_ossl_send() function
already did this.

moved the curl_off_t check to within the --enable-debug block where it belongs since it is a somewhat ugly hack

c-ares call a callback on socket state changes. A better way than the
ares_getsock() to get full control over the socket state.

#ifdef around WSAEDISCON in strerror.c.

(more logical).

HAVE_PROCESS_H added for all except scc.

systems

transfers. They are done on non-windows systems and translate CRLF to LF.

the stream (wrongly) lacks a proper zlib header. This seems to be the case on
too many actual server implementations.

to be accurate on this.

can and will use more than one socket

arguments work properly - and the option is not harmful for the rest of the
curl build either!

to allow/support character conversions

the control connection when using FTP, for example when you remove an easy
handle from a multi stack.

to my previous brain-damaged version)

one

use correct version var.