at: Add AC_COPYRIGHT macro

Signed-off-by: Mark Grant <[email protected]>

configure.ac

@@ -84,6 +84,7 @@
 #				git tree then use git describe to add	#
 #				further package version information.	#
 # 22/11/2021	MG	1.1.6	Tighten SPDX tag.			#
+#				Add AC_COPYRIGHT macro.			#
 #									#
 #########################################################################
 
@@ -94,6 +95,10 @@
 #					#
 #########################################
 
+AC_COPYRIGHT([Copyright (C) 2014-2021  Mark Grant
+	      This script is free to copy or distribute under the terms set out
+	      in the package license. See COPYING for details.])
+
 AC_REVISION([$Revision: 1.1.6 $])
 
 AC_PREREQ([2.69])