dco: move availability check to the end of check_option_conflict() function

dco: move availability check to the end of check_option_conflict() function

To better arrange the order DCO option conflict messages are printed, we
decided to first perform all needed checks on provided options and, only
at the end, if no conflict was detected, to check if DCO is really
available on the system.

This way a user gets prompted with all warnings about their
configuration first and, when everything is fixed, they will see if DCO
is available or not.

While at it, compress the first check in just one if to make the code
simpler.

Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20220802130312.18871-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg24783.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>