[PATCH] [lld] add calls to nativereader/nativewriter

[kledzik at apple.com]

  We should not transfer ownership of atoms between files.  That will be slow and require a way to tell each atoms its new owner, which may cause other problems with shared resources.

  How about have Resolver should return a std::unique_ptr<MutableFile>.  Then have the Pass method take:
    virtual void perform(std::unique_ptr<MutableFile> &file);
  So a Pass can either just modify the existing file's atoms, or completely replace the whole file by moving a new File onto the file parameter.

http://llvm-reviews.chandlerc.com/D1955