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.

struct Foo { int a, b, c; union Data { } Data data; }
struct Bar { int a, b; }
struct Baz { int a; union { Foo foo; Bar bar; } }
void test() { Baz baz; if (baz.bar.a) return; }