Tag build swift-DEVELOPMENT-SNAPSHOT-2017-01-04-a
Merge remote-tracking branch 'origin/swift-3.1-branch' into stable

* origin/swift-3.1-branch:
  [ThinLTO] Fix "||" vs "|" mixup.
  [ThinLTO] Save 8B per summary entry by rearranging the fields (NFC)
  IR: Eliminate non-determinism in the module summary analysis.
  [ThinLTO] Thin link efficiency: More efficient export list computation