name resolves when c-ares is used for resolving.

Some systems poll function sets POLLHUP in revents without setting
POLLIN, and sets POLLERR without setting POLLIN and POLLOUT. In some
libcurl code execution paths this could trigger busy wait loops with
high CPU usage until a timeout condition aborted the loop.

The reverted patch addressed the above issue for a very specific case,
when awaiting c-ares to resolve. A libcurl-wide fix superceeds this one.

http://cool.haxx.se/cvs.cgi/curl/lib/select.c.diff?r1=1.52&r2=1.53

 This fixes a loop problem with high CPU usage.

setup_once.h.  Inclusion of each header file is based on the definition of
NEED_MALLOC_H and NEED_MEMORY_H respectively.

  enabled, we can now take advantage of its brand new AF_UNSPEC support in
  ares_gethostbyname(). This makes test case 241 finally run fine for me wtih
  this setup since it now parses the "::1 ip6-localhost" line fine in my
  /etc/hosts file!

which now also takes a protocol address family argument.

with ipv6-enabled c-ares

  edited it slightly. Now you should be able to use IPv6 addresses fine even
  with libcurl built to use c-ares.

while () => while()
and some other minor re-indentings

bug #1733955

to find that it crashed miserably, and this was due to some select()isms left
in the code. This was due to API restrictions in c-ares 1.3.x, but with the
upcoming c-ares 1.4.0 this is no longer the case so now libcurl runs much
better with c-ares and the multi interface with > 1024 file descriptors in
use.

uses poll() when a fine poll() is available, so now libcurl can be
built without select() support at all if a fine poll() is available.

since they're already included through "setup.h".

  and CURLOPT_CONNECTTIMEOUT_MS that, as their names should hint, do the
  timeouts with millisecond resolution instead. The only restriction to that
  is the alarm() (sometimes) used to abort name resolves as that uses full
  seconds. I fixed the FTP response timeout part of the patch.

  Internally we now count and keep the timeouts in milliseconds but it also
  means we multiply set timeouts with 1000. The effect of this is that no
  timeout can be set to more than 2^31 milliseconds (on 32 bit systems), which
  equals 24.86 days.  We probably couldn't before either since the code did
  *1000 on the timeout values on several places already.

c-ares name resolves, but now we do!

Simplify check for NEED_MALLOC_H, and make more explicit that NEED_MALLOC_H shall be defined if <malloc.h> header file must be included even when including <stdlib.h>.

Curl_freeaddrinfo() and Curl_ip2addr().

(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.

(more logical).

code rearrange to fit the future better.