- Fix GnuTLS code for CURL_SSLVERSION_TLSv1_2 that broke when the
TLS 1.3 support was added in 6ad3add6.

- Homogenize across code for all backends the error message when TLS 1.3
is not available to "<backend>: TLS 1.3 is not yet supported".

- Return an error when a user-specified ssl version is unrecognized.

---

Prior to this change our code for some of the backends used the
'default' label in the switch statement (ie ver unrecognized) for
ssl.version and treated it the same as CURL_SSLVERSION_DEFAULT.

Bug: https://curl.haxx.se/mail/lib-2016-11/0048.html
Reported-by: Kamil Dudka

If SPNEGO fails, cleanup the negotiate handle right away.

Fixes #1115

Signed-off-by: Isaac Boukris <iboukris@gmail.com>
Reported-by: ashman-p

It would always use precision 1 instead of reading it from the argument
list as intended.

Reported-by: Ray Satiro

Bug: #1113

Reported-by: Frank Gevaerts

... with nss-3.26.0 and newer

Reported-by: Daniel Stenberg

BoringSSL supports TLSv1.3 already, but these changes don't seem to be anough
to get it working.

Revert the change from ce8d0948 but use the new function

Reported-by: Kamil Dudka
Bug: https://github.com/curl/curl/commit/ce8d09483eea2fcb1b50e323e1a8ed1f3613b2e3#commitcomment-19666146

Fully implemented with the NSS backend only for now.

Reviewed-by: Ray Satiro

Fully implemented with the NSS backend only for now.

Reviewed-by: Ray Satiro

... but make sure we use at least TLSv1.0 according to libcurl API

Reported-by: Cure53
Reviewed-by: Ray Satiro

We're mostly saying just "curl" in lower case these days so here's a big
cleanup to adapt to this reality. A few instances are left as the
project could still formally be considered called cURL.

Previously, we just ignored "Connection" header field.  But HTTP/2
specification actually prohibits few more header fields.  This commit
ignores all of them so that we don't send these bad header fields.

Bug: https://curl.haxx.se/mail/archive-2016-10/0033.html
Reported-by: Ricki Hirner

Closes https://github.com/curl/curl/pull/1092

Fixes #1107

Reported-by: Adam Piggott

Mirrors the autotools behavior introduced with curl-7_50_3-83-ga34c7ce7.

Fixes #1089

- Call Curl_initinfo on init and duphandle.

Prior to this change the statistical and informational variables were
simply zeroed by calloc on easy init and duphandle. While zero is the
correct default value for almost all info variables, there is one where
it isn't (filetime initializes to -1).

Bug: https://github.com/curl/curl/issues/1103
Reported-by: Neal Poole

Now showing microsecond resolution.

Closes #1106

Regression added in 62a8095e

Reported-by: Tony Kelman

Discussed in #1087

Reported-by: bemoody

Fixes #1104

and change URL to use https

Reported-by: Bruce Stephens

Fixes #1098

Follow-up to 502acba2

Coverity CID 1374359 pointed out the unused result value.

Coverity CID 1374358

.. because including those headers helps Visual Studio's Intellisense.

..because they're no longer needed in the tool build. strcase is still
built by the libcurl project and exports curl_str(n)equal which is used
by the curl tool.

Bug: https://github.com/curl/curl/commit/9363f1a#all_commit_comments

... and now it avoids using the libcurl toupper() function

follow-up to 46133aa5

...to use the public function curl_strnequal(). This isn't ideal because
it adds extra overhead to any internal calls to checkprefix.

follow-up to 95bd2b3e