Function nginx::RSA_meth_set_priv_enc

pub unsafe extern "C" fn RSA_meth_set_priv_enc(
    rsa: *mut RSA_METHOD, 
    priv_enc: Option<unsafe extern "C" fn(flen: c_int, from: *const c_uchar, to: *mut c_uchar, rsa: *mut RSA, padding: c_int) -> c_int>
) -> c_int