_libssh2_openssl_crypto_init() goes down an OpenSSL > 1.1.0 codepath when using Libressl because Libressl defines OPENSSL_VERSION_NUMBER as 0x20000000L, but it should go down the other codepath.

Please use:

#if (OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBSSH2_LIBRESSL))