Fix advance_ext

[tvorogme]

Such TLB:

_ a:(## 64) b:^# = A;
_ a:A = T;

Will generate:

---

bool skip(vm::CellSlice& cs) const override {
  return cs.advance_ext(0x10040);
}

Which has arguments: bits: bits_refs >> 16 and refs: bits_refs & 0xffff

bool CellSlice::advance_ext(unsigned bits_refs) {
  return advance_ext(bits_refs >> 16, bits_refs & 0xffff);
}

But it'll also generate:

bool T::unpack(vm::CellSlice& cs, T::Record& data) const {
  return cs.fetch_subslice_ext_to(0x10040, data.a);
}

Which has arguments: bits: size & 0xffff and refs: size >> 16

td::Ref<CellSlice> CellSlice::fetch_subslice_ext(unsigned size) {
  return fetch_subslice(size & 0xffff, size >> 16);
}

I've checked all current block.tlb scheme and as I understand bagged skip methods are not calling in cpp code. But block-auto.cpp contains invalid skip methods for 59 types. This can lead to random skip size of bits & refs for types.

[05373160476]

tvorogme:patch-5