Added empty build.gradle files for arm64 and s390x because the gradle assemble task fails without them.

Author: evankielley

distribution/docker/docker-arm64-export/build.gradle

@@ -0,0 +1,13 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ *
+ * Modifications Copyright OpenSearch Contributors. See
+ * GitHub history for details.
+ */
+
+// This file is intentionally blank. All configuration of the
+// export is done in the parent project.

distribution/docker/docker-s390x-export/build.gradle

@@ -0,0 +1,13 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ *
+ * Modifications Copyright OpenSearch Contributors. See
+ * GitHub history for details.
+ */
+
+// This file is intentionally blank. All configuration of the
+// export is done in the parent project.