[Format] Add machine-readable SPDX license ID to clang-format.el

git-svn-id: svn://svn.chromium.org/llvm-project/cfe/trunk/tools/clang-format@374864 0b72dbe1-c17f-4bc7-b9db-2b4152be0356
diff --git a/clang-format.el b/clang-format.el
index 0b9dc8d..3096ec1 100644
--- a/clang-format.el
+++ b/clang-format.el
@@ -2,6 +2,7 @@
 
 ;; Keywords: tools, c
 ;; Package-Requires: ((cl-lib "0.3"))
+;; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 ;;; Commentary: