[giac] inequality conversion improvement, eg output from Solve[x (x-1)(x-2)(x-3)(x-4)(x-5) < 0]

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25598 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e