message: tls: update BoringSSL to (3497).
diff: REPOSITORY_LOCATIONS = dict(
  boringssl = dict(
  # Use commits from branch "chromium-stable-with-bazel"
  - commit = "372daf7042ffe3da1335743e7c93d78f1399aba7", # chromium-68.0.3440.75
  + commit = "ab36a84b91b3116bacc85973995504818748d8a9", # chromium-69.0.3497.81
  remote = "https://github.com/google/boringssl",
  ),
  com_google_absl = dict(
  