message: Make BAZEL_CXXOPTS an environment variable again.
diff: @@ -20,7 +20,7 @@ source ./.github/settings.sh
  # TODO(b/171679296): re-enable c++11 support
  # by downgrading kythe build requirements.
  -BAZEL_CXXOPTS="-std=c++17"
  +export BAZEL_CXXOPTS="-std=c++17"
  # Reduce the verbosity of progress output on CI
  BAZEL_OPTS="-c opt --show_progress_rate_limit=10.0"
  