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

[Shankar Kalpathi Easwaran]

  for darwin/hello-world.objtxt :-

  The reference target was set to an empty string :-

     - ref-name:        L000
      scope:           hidden
      type:            stub-helper
      content:         [ 68, 00, 00, 00, 00, E9, 00, 00, 00, 00 ]
      references:
        - kind:            lazyImmediate
          offset:          1
          target:          ''


  With elf files tests,

  a) some of the relocations were set to unknown as the i386 sub target doesnot have all the relocations in it.
  b) some of the attributes were not preserved by the yaml files (section permissions)

  With pecoff :-

  a) invalid relocation kind
  b) bad enum value raised from yaml reader

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