Changes imported from Abseil "staging" branch:

  - f679f7de2957ac4dca0a862d04f1165d2f503525 Merge GitHub PR #78: Fix typo in thread_identity.h by Derek Mauro <dmauro@google.com>
  - 369cbefc9ebb8503e3c25b1516c856dab3bed7ac Minor refactor of operator-(uint128). by Alex Strelnikov <strel@google.com>
  - fba0f8c33b051d90936ad0fcaa4bea83f554bf8d Merge GitHub PR #75: Fix typo in per_thread_tls.h by Derek Mauro <dmauro@google.com>
  - 76d5d25a54ab93c1ea3bc74b5a28ba335b0f2bab Implement InlinedVector::shrink_to_fit() method. by Abseil Team <absl-team@google.com>

GitOrigin-RevId: f679f7de2957ac4dca0a862d04f1165d2f503525
Change-Id: I03b39fdbd70c00a455d98d949d413dd7c8019578