[PATCH] Write references to Native format in NativeReferenceIvarsV2.

[Rui Ueyama]

  Fine. Then let's break the compatibility of V1.

  Looking at the other structs in NativeFileFormat.h, all file offsets are in
  uint32_t, so NativeFormat seems to be a 32-bit file format. Here's the
  definition of NativeReferencesIvarsV1.

  struct NativeReferenceIvarsV1 {
    uint16_t  offsetInAtom;
    int16_t  kind;
    uint16_t  targetIndex;
    uint16_t  addendIndex;
  };

  Here's what I'm going to change.

   - targetIndex needs changing to uint32_t
   - offsetInAtom also needs changing to uint32_t, because otherwise there's
  no way to represent a relocation pointing to a location 65535 or more bytes
  far from the beginning of an atom
   - addendIndex needs changing to uint32_t because of the similar reason as
  offsetInAtom. It's unlikely there's a file containing so much different
  addends. However, Native format is a general format that have to be able to
  represent any file that could be given as a valid input. And if addend has
  32 bit, we can directly store addend to that field.

  So I'd suggest using this data structure.

  struct NativeReferenceIvarsV1 {
    uint32_t  offsetInAtom;
    uint32_t  targetIndex;
    uint32_t  addend;
    int16_t  kind;
    int16_t  _pad;
  };

  We also should remove NativeReferenceIvarV2 structure as it's not used by
  anyone.

http://llvm-reviews.chandlerc.com/D2217