Update copyright information and license headers
diff --git a/configure.ac b/configure.ac
index 125c5d2..5260535 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,25 @@
# -*- Autoconf -*-
+# This file is part of ltrace.
+# Copyright (C) 2010,2012 Petr Machata, Red Hat Inc.
+# Copyright (C) 2010,2011 Joe Damato
+# Copyright (C) 2010 Marc Kleine-Budde
+# Copyright (C) 2010 Zachary T Welch
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 2 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
# Process this file with autoconf to produce a configure script.
AC_PREREQ(2.65)