Closes #3698

Follow-up to 520f0b47 which added Alt-Svc support and enabled it by
default for OS400. Since the feature is experimental, it should be
disabled by default.

Ref: https://github.com/curl/curl/commit/520f0b4#commitcomment-32792332
Ref: https://curl.haxx.se/mail/lib-2019-02/0008.html

Closes https://github.com/curl/curl/pull/3688

[ci skip]

Test 311 is now fine, leaving only 313 (CRL) disabled.

Test 313 details can be found here:
https://github.com/wolfSSL/wolfssl/issues/1546

Closes #3697

Fixes #3692
Closes #3692

Reported-by: nianxuejie on github
Assisted-by: Nick Zitzmann
Assisted-by: Jay Satiro
Fixes #3689
Closes #3690

The threaded-shared-conn.c example turned into test case. Only works if
pthread was detected.

An attempt to detect future regressions such as e3a53e3e

Closes #3687

Although experimental, enable it in the platform config file.
Upgrade ILE/RPG binding.

- make sure an already "owned" connection isn't returned unless
  multiplexed.

- clear ->data when returning the connection to the cache again

Regression since 7.62.0 (probably in commit 1b76c389)

Bug: https://curl.haxx.se/mail/lib-2019-03/0064.html

Closes #3686

AmiSSL is an Amiga native library which provides a wrapper over OpenSSL.
It also requires all programs using it to use bsdsocket.library
directly, rather than accessing socket functions through clib, which
libcurl was not necessarily doing previously. Configure will now check
for the headers and ensure they are included if found.

Closes #3677

... in the SSL structure as AmiSSL is using macros for the socket API
functions.

... to match the style already used for compiling, linking
etc. Acknowledges 'make V=1' to enable verbose.

Closes #3681

Suggested-by: Eric Curtin
Improved-by: Dan Fandrich
Ref: #3680

Closes #3683

From a discussion in #3676

Suggested-by: Tim Rühsen

Closes #3682

* Adjusted unit tests 2056, 2057
* do not generally close connections with CURLAUTH_NEGOTIATE after every request
* moved negotiatedata from UrlState to connectdata
* Added stream rewind logic for CURLAUTH_NEGOTIATE
* introduced negotiatedata::GSS_AUTHDONE and negotiatedata::GSS_AUTHSUCC
* Consider authproblem state for CURLAUTH_NEGOTIATE
* Consider reuse_forbid for CURLAUTH_NEGOTIATE
* moved and adjusted negotiate authentication state handling from
  output_auth_headers into Curl_output_negotiate
* Curl_output_negotiate: ensure auth done is always set
* Curl_output_negotiate: Set auth done also if result code is
  GSS_S_CONTINUE_NEEDED/SEC_I_CONTINUE_NEEDED as this result code may
  also indicate the last challenge request (only works with disabled
  Expect: 100-continue and CURLOPT_KEEP_SENDING_ON_ERROR -> 1)
* Consider "Persistent-Auth" header, detect if not present;
  Reset/Cleanup negotiate after authentication if no persistent
  authentication
* apply changes introduced with #2546 for negotiate rewind logic

Fixes #1261
Closes #1975

The check that prevents payload from sending in case of authentication
doesn't check properly if the authentication is done or not.

They're cases where the proxy respond "200 OK" before sending
authentication challenge. This change takes care of that.

Fixes #2431
Closes #3669

Pointed out by codacy

Closes #3672

Coverity warned for two potentional "Use after free" cases. Both are false
positives because the memory wasn't used, it was only the actual pointer
value that was logged.

The fix still changes the order of execution to avoid the warnings.

Coverity CID 1443033 and 1443034

Closes #3671

For the Linux builds, GCC 8 and 7 and clang 7 were installed, but the
new GCC versions were only used for the coverage build and for building
nghttp2, while the new clang version was not used at all.

BoringSSL needs to use the default GCC as it respects CC, but not CXX,
so it would otherwise pass gcc 8 options to g++ 4.8 and fail.

Also remove GCC 7, it's not needed anymore.

Ref: https://docs.travis-ci.com/user/languages/c/#c11c11-and-beyond-and-toolchain-versioning

Closes https://github.com/curl/curl/pull/3670

Closes https://github.com/curl/curl/pull/3670

.. and for Windows also call WSACleanup since we call WSAStartup.

The example is to demonstrate handling the socket independently of
libcurl. In this case libcurl is not responsible for creating, opening
or closing the socket, it is handled by the application (our example).

Fixes https://github.com/curl/curl/pull/3663

This code was once used for the non multi-interface using code path, but
ever since easy_perform was turned into a wrapper around the multi
interface, this code path never runs.

Closes #3666

- Inherit SSL options for the doh handle but not SSL client certs,
  SSL ALPN/NPN, SSL engine, SSL version, SSL issuer cert,
  SSL pinned public key, SSL ciphers, SSL id cache setting,
  SSL kerberos or SSL gss-api settings.

- Fix inheritance of verbose setting.

- Inherit NOSIGNAL.

There is no way for the user to set options for the doh (DNS-over-HTTPS)
handles and instead we inherit some options from the user's easy handle.

My thinking for the SSL options not inherited is they are most likely
not intended by the user for the DOH transfer. I did inherit insecure
because I think that should still be in control of the user.

Prior to this change doh did not work for me because CAINFO was not
inherited. Also verbose was set always which AFAICT was a bug (#3660).

Fixes https://github.com/curl/curl/issues/3660
Closes https://github.com/curl/curl/pull/3661

Reproduced bug #3649
Closes #3659

This reverts commit 3773de37.

Regression shipped in 7.64.0
Fixes #3649

To not "collide" or use up the regular curl_ name space. Also makes them
easier to detect in helper scripts.

Closes #3656

Clarify the language and simplify.

Reported-by: Daniel Lublin
Closes #3658

Closes #3145

Both seem to be false positives but we don't like warnings.

Closes #3646