Use mingw compile definition also to unit tests

Use mingw compile definition also to unit tests

Currently we only apply the defines for windows APIs and Unicode to
OpenVPN itself. We should rather treat the unit tests the same as
our main binary to reduce potential differences.

Change-Id: Ie5aa643ab6190262f7c8b9e614bedb398e85859b
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20240116131831.31217-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28019.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>