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 bug44;

struct rgb
{
    long l;
}

void foo()
{
}

rgb test() {
  scope(exit) foo();
  return rgb();
}

void main()
{
    rgb r = test();
}