Return engine implementation but use legacy OpenSSL
    
    Engine interface were deprecated in OpenSSL and therefore removed from
    normal compilation. But it is possible to compile on OpenSSL with compat
    define. That disables deprecation warnings and use functions same as for
    OpenSSL 1.1. That is required to keep working engine pkcs11 support.
    
    Otherwise loading keys via ENGINE_load_private_key would always fail.
    
    Resolves: rhbz:#2122010