add C++ aarch64 kokoro configuration

kokoro/linux/cpp_aarch64/build.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+#
+# This is the top-level script we give to Kokoro as the entry point for
+# running the "continuous" and "presubmit" jobs.
+
+set -ex
+
+# Change to repo root
+cd $(dirname $0)/../../..
+
+kokoro/linux/aarch64/test_cpp_aarch64.sh

kokoro/linux/cpp_aarch64/continuous.cfg

@@ -0,0 +1,5 @@
+# Config file for running tests in Kokoro
+
+# Location of the build script in repository
+build_file: "protobuf/kokoro/linux/cpp_aarch64/build.sh"
+timeout_mins: 120

kokoro/linux/cpp_aarch64/presubmit.cfg

@@ -0,0 +1,5 @@
+# Config file for running tests in Kokoro
+
+# Location of the build script in repository
+build_file: "protobuf/kokoro/linux/cpp_aarch64/build.sh"
+timeout_mins: 120