From Eddy Offermann:

Instead of warning of a under/over flow in TDecompLU::InvertLU and then
returning a determinant of zero , we now return the calculated value .
Now the user will not be confused anymore and think that the matrix
was singular .


git-svn-id: http://root.cern.ch/svn/root/trunk@10711 27541ba8-7e3a-0410-8455-c3a389f83636