Changed some hardcoded offset/alignment for classes in DMD, broke offsets for 64bits. Changed ClassInfo generation to no longer access the default initializer of ClassInfo, fixes problems with index mismatch.

module union1;

union U
{
    float f;
    int i;
}

void main()
{
    float f = 2;
    U u = U(f);
    assert(u.i == *cast(int*)&f);
}