rawgit.com asks to use the domain cdn.rawgit.com for production

See #900

Closes #740

The FreeBSD Port security/ca_root_nss installs the Mozilla NSS CA bundle
to /usr/local/share/certs/ca-root-nss.crt. Use this bundle in the
discovery process.

This change also removes the former FreeBSD path that has been obsolete
for 8 years since this FreeBSD ports commit:
https://svnweb.freebsd.org/ports/head/security/?view=revision&revision=215953

Closes #894

Another follow up for crypt32.lib linking with winssl

follow-up from 120bf29e

Necessary since 6cabd785

Necessary since 6cabd785

Fixes #853

Closes #854

Broken since 6cabd785, which adds use of the Curl_extract_certinfo
function from the x509asn1.c file.

... and save the typedef'ed names for headers and external APIs.

Instead of typedef'ing to void, typedef to their corresponding actual
struct names to allow compilers to type-check.

Assisted-by: Reinhard Max

Prior to this change we called Curl_ssl_getsessionid and
Curl_ssl_addsessionid regardless of whether session ID reusing was
enabled. According to comments that is in case session ID reuse was
disabled but then later enabled.

The old way was not intuitive and probably not something users expected.
When a user disables session ID caching I'd guess they don't expect the
session ID to be cached anyway in case the caching is later enabled.

Closes #883

CMake build now using BUILD_TESTING=ON/OFF (default is OFF) to build
tests and enabling CTest integration. Options BUILD_CURL_TESTS and
BUILD_DASHBOARD_REPORTS was removed.

Closes #882

Reviewed-by: Brad King

Closes #887

Some builds of GCC produce output on both stdout and stderr when --help
--verbose is used.  The 2>&1 redirection caused them to be arbitrarily
interleaved with each other because of stream buffering.  Consequently,
grep failed to match the fvisibility= string in the mixed output, even
though the string was present in GCC's standard output.

This led to silently disabling symbol hiding in some builds of curl.

The HTTP/2 tests brought with commit bf05606e were using the internal
name 'http2' for the HTTP/2 server, while in fact that name was already
used for the second instance of the HTTP server. This made tests using
the second instance (like test 2050) fail after a HTTP/2 test had run.

The server is now known as HTTP/2 internally and within the <server>
section in test cases. 1700, 1701 and 1702 were updated accordingly.

Regression introduced in 5f5b6263 (released in 7.48.0)

Reported-by: Fabian Ruff
Fixes #875

Bug: https://github.com/curl/curl/pull/874
Reported-by: Sergei Nikulov

When CURLOPT_POSTFIELDS is set to an empty string libcurl will send a
zero-byte POST. Prior to this change it was documented as sending data
from the read callback.

This also changes the wording of what happens when empty or NULL so that
it's hopefully easier to understand for people whose primary language
isn't English.

Bug: https://github.com/curl/curl/issues/862
Reported-by: Askar Safin

- Remove some erroneous text.

Closes https://github.com/curl/curl/pull/865

- Enable protocol family logic for IPv6 resolves even when support
for synthesized addresses is enabled.

This is a follow up to the parent commit that added support for
synthesized IPv6 addresses from IPv4 on iOS/OS X. The protocol family
logic needed for IPv6 was inadvertently excluded if support for
synthesized addresses was enabled.

Bug: https://github.com/curl/curl/issues/863
Ref: https://github.com/curl/curl/pull/866
Ref: https://github.com/curl/curl/pull/867

Use getaddrinfo() to resolve the IPv4 address literal on iOS/Mac OS X.
If the current network interface doesn’t support IPv4, but supports
IPv6, NAT64, and DNS64.

Closes #866
Fixes #863

1701 and 1702

... and have test 1700 use that to strip out the nghttpx server: headers

It requires that 'nghttpx' is in the PATH, and it will run the tests
using nghttpx as a front-end proxy in front of the standard HTTP/1 test
server. This uses HTTP/2 over plain TCP.

If you like me have nghttpx installed in a custom path, you can run test 1700
like this:

$ PATH=$PATH:$HOME/build-nghttp2/bin/ ./runtests.pl 1700