changed macro name, moved and renamed script to become docs/libcurl/has.pl,
generate code that is checksrc compliant

RFC 7540 section 8.1.2.2 states: "An endpoint MUST NOT generate an
HTTP/2 message containing connection-specific header fields; any message
containing connection-specific header fields MUST be treated as
malformed"

Closes #401

and some general cleaning up

This fixes another run-time check failure because of a narrowing cast on
Visual C++.

Closes #408

- Warn that cookies without a domain are sent to any domain:
CURLOPT_COOKIELIST, CURLOPT_COOKIEFILE, --cookie

- Note that imported Set-Cookie cookies without a domain are no longer
exported:
CURLINFO_COOKIELIST, CURLOPT_COOKIEJAR, --cookie-jar

tool_sdecls.h:139 warning: comma at end of enumerator list

Introduced in commit 59f3f92b this function is only implemented when
CURL_DISABLE_CRYPTO_AUTH is not defined. As such we shouldn't define
the function in the header file either.

In places the "host name" and "realm" variable was referred to as
"instance" whilst in others it was referred to as "host".

Turns out HMAC_Init is now deprecated in openssl master (and I spelled
HMAC_Init_ex wrong in previous commit)

Set HAVE_DES_SET_ODD_PARITY when using OpenSSL/BoringSSL as native
Windows builds don't use the autoconf tools.

curl_ntlm_core.c:150: warning 'Curl_des_set_odd_parity' undefined;
                      assuming extern returning int

But kept the original author, when they were specified in a comment, as
the initial copyright holder.

Put braces around empty "if" body in libcurl.m4 check to avoid warning:

        suggest braces around empty body in an 'if' statement

and make it work with -Werror builds.

Closes #402

Closes #398

remove redundant '}'

Closes #399

It isn't always clear to the user which options that cause the HTTP
methods to conflict so by spelling them out it should hopefully be
easier to understand why curl complains.

Closes #395

... since HTTP is forbidden to return any such.

This patch addresses known bug #76, where on 64-bit Windows SOCKET is 64
bits wide, but long is only 32, making CURLINFO_LASTSOCKET unreliable.

Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>

Leftovers from when we removed the private socket hash.

Coverity CID 1317365, "Logically dead code"

Coverity CID 1317367, "Missing break in switch"

"Explicit null dereferenced (FORWARD_NULL)"

Coverity CID 1317366