Re-generate configury with autoconf 2.64

* abigail.m4: Add licence header.
	* configure.ac: Re-generate configure script with autoconf 2.64
	like for GCC.

abigail.m4

@@ -1,3 +1,26 @@
+# Copyright (C) 2013 Free Software Foundation, Inc.
+# 
+# This file is part of the GNU Application Binary Interface Generic
+# Analysis and Instrumentation Library (libabigail).  This library 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 3, or (at your option) any
+# later version.
+# 
+# This library 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.
+# 
+# Under Section 7 of GPL version 3, you are granted additional
+# permissions described in the GCC Runtime Library Exception, version
+# 3.1, as published by the Free Software Foundation.
+# 
+# You should have received a copy of the GNU General Public License
+# and a copy of the GCC Runtime Library Exception along with this
+# program; see the files COPYING3 and COPYING.RUNTIME respectively.
+# If not, see <http://www.gnu.org/licenses/>.
+
 # ABIGAIL_INIT
 #
 # Handle the detection of the libabigail header and library files on