Fix '--cipher none --cipher' crash

Fix '--cipher none --cipher' crash

As reported in trac #699, OpenVPN crashes when an "--cipher none" option
is followed by "--cipher" (without arguments).  Fix this by removing the
redudant ciphername_defined and authname_defined members of struct options,
and remove support to specify --cipher or --auth without an argument.  That
not only fixes the issue, but also cleans up the code a bit.

v2: don't print a deprecating warning (we'll do that in the 2.3 branch),
    but just rip out support for --cipher and --auth without an argument.

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1469541338-1530-1-git-send-email-steffan.karger@fox-it.com>
URL: http://article.gmane.org/gmane.network.openvpn.devel/12106
Signed-off-by: Gert Doering <gert@greenie.muc.de>