[giac] enable both methods of loading the dynamic library (one as fallback)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25341 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
4.9.128.0

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25342 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e