cleanup: Remove RPM openvpn.spec build approach

cleanup: Remove RPM openvpn.spec build approach

Linux packaging is quite a comprehensive task these days, with many
Linux distributions and each with their own packaging guidelines.  In
addition OpenVPN is packaged for most important Linux distributions
already.

The OpenVPN developers is not capable of keeping track of how all the
various recommend packaging guidelines evoloves and our RPM build
process is no longer consistent with guidelines from Fedora, RHEL or
SUSE packaging.  We also don't receive any updates improving this
situation.  Most likely due to packaging being handled fairly well by
the Linux distributions directly.

In addition comes systemd into play, which more and more Linux
distributions embraces - and even our own RPM openvpn.spec file didn't
account for that move.

This removes all RPM related packaging files and updates the INSTALL
file with pointers to several popular Linux distributions with
accessible information of the OpenVPN packages they provide.  Linux
distributions is most likely much better at keeping the packaging
up-to-shape much better than we.

Signed-off-by: David Sommerseth <davids@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20190220131906.22970-1-davids@openvpn.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18222.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>