Avoid having to update this manually.

We should scope these as narrowely as possible to avoid side effects.

This is the standard method of finding it on Unix systems, so make sure
we use it. Still keep a fallback, though, for other systems, e.g.
Windows.

FFMPEG is needed by the RFB library, so all the details about it should
only be applied there and not for other components.

We need this function to deal with pkgconfig files properly, but
unfortunately it doesn't exist until CMake 3.13, and we need to support
CMake 3.10. So add a hacky compatibility function for older systems.

Enable this automatically for developers so we increase the chance of
these problems getting caught. There is a risk of overhead though so
keep them disabled for release builds.

The migration from 32-bit to 64-bit has long passed. Let's get rid of
all distinctions as native applications it the norm now.

Linux implementation using ffmpeg

It's difficult to support both old and new versions, so raise the
requirement to the oldest that is commonly used, which is CMake 3.10.2
on Ubuntu 18.04.

They define macros such as "check()" which causes our code to break as
we have methods with that name.

Without this change I get CMake errors due to use of ${FLTK_INCLUDE_DIR}
and references to the non-existent vncviewer target.

These are incompatible with functions such as gettext() as clang hasn't
implemented the function attribute function_arg.

It's just confusing when this is split over two directories.

This is the current upstream so let's make use of it to get the latest
in features and fixes.

This makes our builds directly compatible with most distributions
without packagers/users having to specify extra flags.

This sets up a more correct session as there are key tasks that
need to be performed by PAM. E.g. systemd will allocate cgroups
and start base services.

In order to easily handle this as a system service the mapping of
displays is now done via a configuration file.

It is present on all UNIX systems anyway, so let's simplify things.
We will need it for more proper session startup anyway.

It is the most common init system these days so it should not be
hidden in the contrib/ directory.

This also removes all old SysV files from the contrib packages.

Install some example files to make things more easily discoverable.

because it is not only platform independent
but also allows to override the build date
This helps to make tigervnc builds reproducible

See https://reproducible-builds.org/ for why this is good

Also adds UTC flag, to be independent of timezone.
Also changes JAVA_DATE format to ISO-8601 date format.

Requires cmake-2.8.11+ from 2013

These are not allowed in C++, and have been made optional in C11.
So let's just get rid of them and any issues they may cause.

Avoid that the check_c_source_compiles tests fails due to unused
variables, since Debug adds -Werror.

The compiler might default to something older, so make sure we get
the features we need.

cmake_policy() by itself raises the minimum requirement on CMake.
We want it to be optional though, so add the necessary if() around
it.

The builtin causes errors in the test, and we're also trying to
determine if it is provided by libc or not.

We don't modify the link interface directly so these warnings are
just useless noise. We could in theory use the new naming instead,
but at least CMake 2.8.12 is buggy and screws up the link when that
policy is active.

It just makes CMake error out rather than continue without NLS
support.

We need the newer versions of Windows to get access to better
thread primitives.

On some systems, the build was picking up jpeglib.h from the system
include directories, and if the system's version of libjpeg[-turbo] used
a different API/ABI version than the one specified in JPEG_LIBRARY, this
led to a "Wrong JPEG library version" error at run time.

Useful for debugging memory leaks and access violations. It is
not available on Windows though, and there is some problem compiling
ObjectiveC++ with it turned on.

Every reasonably current system support getaddrinfo() so get rid
of the legacy fallbacks.

It fails to find stdcall functions, so we need to just hard code
things based on our minimum Windows requirements.