Revert commit r186216 -- it's breaking bots:

  http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/6897/steps/check-all/logs/LLVM%3A%3Aarchive-format.test

Original commit log:
  Fix a off by one error about which members need to use the string
  table.

llvm-svn: 186232