Fix compiler warning: variable was set but never used

Fix compiler warning: clobber ignored

"if(a)" is our style, not "if( a )"

By the use of a the new lib/checksrc.pl script that checks that our
basic source style rules are followed.

Fixed indents, coding conventions and white space edits.

Modified the c-ares completion callback function to again NOT read the
conn data when the ares handle is being taken down as then it may have
been freed already.

Introducing an internal API for handling of different async resolver
backends.

Massively reduce #ifdefs all over (23 #ifdef lines less so far)
Moved conversion-specific code to non-ascii.c

1 - make sure to #define macros for cookie functions in the cookie
header when cookies are disabled to avoid having to use #ifdefs in code
using those functions.

2 - move cookie-specific code to cookie.c and use the functio
conditionally as mentioned in (1).

net result: 6 #if lines removed, and 9 lines of code less

curl_easy_duphandle() was not properly duping the ares channel. The
ares_dup() function was introduced in c-ares 1.6.0 so by starting to use
this function we also raise the bar and require c-ares >= 1.6.0
(released Dec 9, 2008) for such builds.

Reported by: Ning Dong
Bug: http://curl.haxx.se/mail/lib-2010-08/0318.html

Curl_getconnectinfo() is changed to return a proper curl_socket_t for
the last socket so that it'll work more portably (and cause less
compiler warnings).

Howard Chu brought the bulk work of this patch that properly
moves out the sending and recving of data to the parts of the
code that are properly responsible for the various ways of doing
so.

Daniel Stenberg assisted with polishing a few bits and fixed some
minor flaws in the original patch.

Another upside of this patch is that we now abuse CURLcodes less
with the "magic" -1 return codes and instead use CURLE_AGAIN more
consistently.

The necessary libssh2 functions require libssh2 1.2.5 or later.

fix printf-style format strings

into curl_rand.c and curl_rand.h

fix compiler warning

KEEP_RECV to better match the general terminology: receive and send is what we
do from the (remote) servers. We read and write from and to the local fs.

  curl_easy_duphandle did not necessarily duplicate the CURLOPT_COOKIEFILE
  option. It only enabled the cookie engine in the destination handle if
  data->cookies is not NULL (where data is the source handle). In case of a
  newly initialized handle which just had the cookie support enabled by a
  curl_easy_setopt(handle, CURL_COOKIEFILE, "")-call, handle->cookies was
  still NULL because the setopt-call only appends the value to
  data->change.cookielist, hence duplicating this handle would not have the
  cookie engine switched on.

  We also concluded that the slist-functionality would be suitable for being
  put in its own module rather than simply hanging out in lib/sendf.c so I
  created lib/slist.[ch] for them.

Curl_sspi_global_init() and Curl_sspi_global_cleanup() which previously were
named Curl_ntlm_global_init() and Curl_ntlm_global_cleanup() in http_ntlm.c
Also adjusted socks_sspi.c to remove the link-time dependency on the Windows
SSPI library using it now in the same way as it was done in http_ntlm.c.

curl_easy_reset() by creating Curl_init_userdefined(). This had the side effect
of fixing curl_easy_reset() so it now also resets CURLOPT_FTP_FILEMETHOD and
CURLOPT_SSL_SESSIONID_CACHE

  duphandle+curl_mutli" (http://curl.haxx.se/bug/view.cgi?id=2416182) showed
  that curl_easy_duphandle() wrongly also copied the pointer to the connection
  cache, which was plain wrong and caused a segfault if the handle would be
  used in a different multi handle than the handle it was duplicated from.

examples that I found in the FreeBSD ports system.

  during certain conditions. I also changed this code to use realloc() based
  on Daniel Fandrich's suggestion.