Add SPDX-License-Identifier headers

Add SPDX-License-Identifier headers to all substantial source files.
Collapse copyright years.  Add some Emacs configuration for files
where the copyright notice is at the end.  Add a test that every
file has SPDX-License-Identifier.

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/client/full-t.in b/tests/client/full-t.in
index 1ad486c..5f7406a 100644
--- a/tests/client/full-t.in
+++ b/tests/client/full-t.in
@@ -8,7 +8,7 @@
 # Copyright 2008, 2010, 2014
 #     The Board of Trustees of the Leland Stanford Junior University
 #
-# See LICENSE for licensing terms.
+# SPDX-License-Identifier: MIT
 
 use strict;
 use warnings;