cmake: enable IPv6 by default if available

ENABLE_IPV6 depends on HAVE_GETADDRINFO or you will get a
Curl_getaddrinfo_ex error. Enable IPv6 by default, disabling it if
struct sockaddr_in6 is not found in netinet/in.h.

Note that HAVE_GETADDRINFO_THREADSAFE is still not set as it needs more
platform checks even though POSIX requires a thread-safe getaddrinfo.

Verified on Arch Linux x86_64 with glibc 2.20-2 and Linux 3.16-rc7.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
tests: move TESTCASES to Makefile.inc, add show for cmake

This change allows runtests.pl to be run from the CMake builddir:

    export srcdir=/tmp/curl/tests;
    perl -I$srcdir $srcdir/runtests.pl -l

In order to make this possible, all test cases have been moved from
Makefile.am to Makefile.inc.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
vtls/*: deprecate have_curlssl_md5sum and set-up default md5sum implementation
gskit: supply dummy randomization function
vtls: remove QsoSSL
Factorize pinned public key code into generic file handling and backend specific
pinning: minor code style policing
singleipconnect: remove dead assignment never used

cppcheck pointed this out.
cleanups: reduce variable scope

cppcheck pointed these out.
CURLOPT_TLSAUTH_*.3: fix reference typos
Implement pinned public key in GSKit backend
OS400: fix bugs in curl_*escape_ccsid() and reduce variables scope
mk-ca-bundle: added SHA-384 signature algorithm

Certificates based on SHA-1 are being phased out[1].
So we should expect a rise in certificates based on SHA-2.
Adding SHA-384 as a valid signature algorithm.

[1] https://blog.mozilla.org/security/2014/09/23/phasing-out-certificates-with-sha-1-based-signature-algorithms/

Signed-off-by: Bruno Thomsen <bth@kamstrup.dk>
sasl_sspi: Fixed Kerberos response buffer not being allocated when using SSO
sasl_sspi: Fixed some typos
httpcustomheader.c: make use of more CURLOPT_HTTPHEADER features

... and only do a single request for clarity.
ntlm: Avoid unnecessary buffer allocation for SSPI based type-2 token
ntlm: Fixed empty/bad base-64 decoded buffer return codes
ntlm: Fixed empty type-2 decoded message info text

Updated the info text when the base-64 decode of the type-2 message
returns a null buffer to be more specific.
test545: make it not use a trailing zero

CURLOPT_COPYPOSTFIELDS with a given CURLOPT_POSTFIELDSIZE does not
require a trailing zero of the data and by making sure this test doesn't
use one we know it works (combined with valgrind).