reactivate scalar_product
reactivate scalar_product

this change had adverse effects on the alpha benchmark (=> find out why)

mndrix/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel