openssl: add crypto_msg(), to easily log openssl errors

openssl: add crypto_msg(), to easily log openssl errors

This works towards removing OpenSSL-specific error printing code from
error.c. The crypto_msg() functions provide convenience wrappers, specific
to OpenSSL. Instead of passing the magical 'M_SSLERR' flag to msg(), a
developer now just calls crypto_msg() to get OpenSSL errors dumped to log.

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1414269324-14102-5-git-send-email-steffan@karger.me>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9199
Signed-off-by: Gert Doering <gert@greenie.muc.de>