Fix loading PKCS12 files on Windows

Fix loading PKCS12 files on Windows

Starting from 2.5.4 we have switched to MSVC builds,
including dependencies such as OpenSSL.

When we link with natively-built OpenSSL .DLLs
(not cross compiled with MinGW), we are expected to include
applink.c, which provides glue between OpenSSL BIO layer
and compiler run-time. This doesn't apply to ARM64.

Failure to do that results in "no OPENSSL_Applink" fatal error
when calling, for example, d2i_PKCS12_fp(), which we do when
loading PKCS12 files.

Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20211006090709.200-1-lstipakov@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg22920.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit af5de933a0633436e0fe00c42464f4a7ab5ac509)