Remove a dead variable from ldmd. (It used to be used to pass an extra -help to ldc when no files were specified, but we handle that in ldc itself now)

module comma;

void main()
{
    int i=0,j=0;
    for (; i<10; i++,j++)
    {
    }
    assert(i == 10);
    assert(j == 10);
}