ref: 180f955e94367d0439cee3d0e7ad7606afab1fb1
dir: /sys/src/ape/lib/openssl/crypto/bn/bn.mul/
We need * bn_mul_comba8 * bn_mul_comba4 * bn_mul_normal * bn_mul_recursive * bn_sqr_comba8 * bn_sqr_comba4 bn_sqr_normal -> BN_sqr * bn_sqr_recursive * bn_mul_low_recursive * bn_mul_low_normal * bn_mul_high * bn_mul_part_recursive # symetric but not power of 2 bn_mul_asymetric_recursive # uneven, but do the chop up.