[giac] more fixes after removing ggmtmpvarx/y/y'/y''/z

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26377 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] fix Vectors_MatrixTimesVector_1 after ggbtmpvarx/y removed

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26378 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e