message: Windows: override msvc-cl config if BAZEL_BUILD_EXTRA_OPTIONS set
  Will allow us to cleanly add a clang-cl build in CI
diff: @@ -25,7 +25,9 @@ if [ ! -e "/$drive/$drive" ]; then
  fi
  BAZEL_STARTUP_OPTIONS="--output_base=c:/_eb"
  -BAZEL_BUILD_OPTIONS="-c opt --config=msvc-cl --show_task_finish --verbose_failures \
  +# Default to msvc-cl if not overridden
  +BAZEL_BUILD_EXTRA_OPTIONS=${BAZEL_BUILD_EXTRA_OPTIONS:---config=msvc-cl}
  +BAZEL_BUILD_OPTIONS="-c opt --show_task_finish --verbose_failures \
  --test_output=errors ${BAZEL_BUILD_EXTRA_OPTIONS} ${BAZEL_EXTRA_TEST_OPTIONS}"
  # Test to validate updates of all dependency libraries in bazel/external and bazel/foreign_cc
  