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().

the crash was that libcurl internally was a bit confused about who owned the
DNS cache at all times so if you created an easy handle that uses a shared
DNS cache and added that to a multi handle it would crash. Now we keep more
careful internal track of exactly what kind of DNS cache each easy handle
uses: None, Private (allocated for and used only by this single handle),
Shared (points to a cache held by a shared object), Global (points to the
global cache) or Multi (points to the cache within the multi handle that is
automatically shared between all easy handles that are added with private
caches).

(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).

as previously it could be holding on to old cached entries longer than
requested.

The tag 'before_ftp_statemachine' was set just before this commit in case
of future need.

errors.

Andy Cedilnik reported. Warning on HP-UX?

allow verbose output during this period. Bertrand Demiddelaer reported and
helped fixing.

precaution to prevent mistakes to lead to buffer overflows.

of typecasts all over

linked list for name resolved data, even on hosts/systems with only IPv4
stacks as this simplifies a lot of code.

a host name that resolves to multiple IP addresses.

memory.h is included everywhere for this.

out of memory (thanks to 'runtests.pl -t')

make the code easier to read

usage.

 threaded name resolves.

now cause the resolve function to return NULL immediately

some bad thinking on my part.

when not using ares.