Function nginx::SSL_CTX_set_client_cert_cb

pub unsafe extern "C" fn SSL_CTX_set_client_cert_cb(
    ctx: *mut SSL_CTX, 
    client_cert_cb: Option<unsafe extern "C" fn(ssl: *mut SSL, x509: *mut *mut X509, pkey: *mut *mut EVP_PKEY) -> c_int>
)