Detect broken RDRAND during initialization

Some CPUs advertise RDRAND in CPUID, but return 0xFFFFFFFF
unconditionally. To avoid locking up later, test RDRAND during
initialization, and if it returns 0xFFFFFFFF, mark it as nonexistent.

Fixes #588.

Fix segmentation fault in CPUID check

Tweak json_parse.c slightly to allow it to build against older json-c versions.

This is intended to provide a way, during development, to test out the memory
and performance impacts of a change.

Move the list of contributors to the AUTHORS file.

add the list of issues& prs closed

Increase coverage

CMakeLists: do not enforce strict prototypes on Windows.

On Windows, or at least when cross-built with Mingw-w64, build fails
because strict prototype fails on an included file (thus nothing we can
do about in json-c code):

> from /home/jehan/dev/src/json-c/json_util.c:44:
> /home/jehan/.local/share/crossroad/roads/w64/json-c/include/minwindef.h:196:3: error: function declaration isn't a prototype [-Werror=strict-prototypes]
>   196 |   typedef INT_PTR (WINAPI *FARPROC) ();
>       |   ^~~~~~~
> /home/jehan/.local/share/crossroad/roads/w64/json-c/include/minwindef.h:197:3: error: function declaration isn't a prototype [-Werror=strict-prototypes]
>   197 |   typedef INT_PTR (WINAPI *NEARPROC) ();
>       |   ^~~~~~~
> /home/jehan/.local/share/crossroad/roads/w64/json-c/include/minwindef.h:198:3: error: function declaration isn't a prototype [-Werror=strict-prototypes]
>   198 |   typedef INT_PTR (WINAPI *PROC) ();
>       |   ^~~~~~~

Let's just disable the errors for Windows build.

Fix CMake tests for enforced strict prototypes.

Arraylist testcase

Enforce strict prototypes.

CMake: Install pkgconfig file in proper location by default

The default location for pkconfig files on most systems is:
  ${CMAKE_INSTALL_LIBDIR}/pkgconfig

Thus the file should get installed in there by default.

Be verbose on failing json_c_version test.

Test coverage for json_c_version.

Small cosmetics.