ossl_curve448_scalar_add
ossl_curve448_scalar_add(scalar1x, scalar, precomputed_scalarmul_adjustment);
ossl_curve448_scalar_add(challenge_scalar, challenge_scalar, nonce_scalar);
void ossl_curve448_scalar_add(curve448_scalar_t out,
ossl_curve448_scalar_add(t1, t1, t2);