script to fail on debian unstable (some specific bash version perhaps?)

AC_CHECK_HEADERS() and the action-if-found since that action is run even if
just one of the six headers is found and I just now fell over a case with
a duplicate file name (a krb4 implementation with an err.h file).

I converted the check to manually make sure three of the headers are present
before considering them fine.

2 - store the time it took to verify it and allow that time to be used as
  %FTPTIME[23] in command lines to allow us to adjust better to slow hosts
  since test 190 failed on my slow solaris machine just because it hadn't
  gotten time to run all the way the test assumed all machines would reach
  before the time-out elapsed.

truly use SSL

checks on the to-be-returned socket to make sure it truly seems to be alive
and well. For SSL connection it (only) uses OpenSSL functions.

seconds even when everything is fine! Now we allow a test server 8 seconds
to respond to still be considered ok.

2 - properly escape certain letters within a DICT word to comply to the RFC2229

things such as C++ compiler actually is a bad thing and since we don't need
that detection I added a work-around, much inspired by a previous patch by
Paolo Bonzini. This also shortens the configure script quite a lot.

autotools project, which optionally (default=yes) uses libcurl on a system
without a (usable) libcurl installation, but not specifying
`--without-libcurl', configure determines correctly that no libcurl is
available, however, the LIBCURL variable gets expanded to `LIBCURL = -lcurl'
in the resulting Makefiles.

David Shaw fixed the flaw.

connects. The state machine was not reset properly so that subsequent
connects using the same handle would fail, and there were two memory leaks.

multi stack and that easy handle had already been used to do one or more
easy interface transfers, as then the code threw away the previously used
DNS cache without properly freeing it.

from Curl_client_write

Fixed handling of retransmitted blocks on transmit
Properly aligned data to transmit within packet
Replaced calls to strerror() with Curl_strerror()

thus works reliably on more platforms.

like this in this source file. The quickfix for now is to provide a simple
version for GnuTLS builds. The GnuTLS version of libcurl doesn't yet allow
fully non-blocking connects anyway so this function doesn't get used.

(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.