Remove openvpn_snprintf and similar functions

Remove openvpn_snprintf and similar functions

Old Microsoft versions did strange behaviour but according to the
newly added unit test and
https://stackoverflow.com/questions/7706936/is-snprintf-always-null-terminating
this is now standard conforming and we can use the normal snprintf
method.

Microsoft own documentation to swprintf also says you nowadays need to
define _CRT_NON_CONFORMING_SWPRINTFS to get to non-standard behaviour.

Change-Id: I07096977e3b562bcb5d2c6f11673a4175b8e12ac
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20240506102710.8976-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28617.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>