BN_init() deprecated from OpenSSL

[kewde]

https://wiki.openssl.org/index.php/Manual:BN_new(3)

BN_new(), BN_clear(), BN_free() and BN_clear_free() are available in all versions on SSLeay and OpenSSL. BN_init() was added in SSLeay 0.9.1b and removed in OpenSSL 1.1.0.