Licence for gnulib.mk slightly vague

[Glenn Morris]

Hi,

The copy of gnulib.mk in Emacs says:

    # This file is free software, distributed under the terms of the GNU
    # General Public License.  As a special exception to the GNU General
    # Public License, this file may be distributed as part of a program
    # that contains a configuration script generated by Autoconf, under
    # the same distribution terms as the rest of that program.

There's no information about which version of the GPL.
m4/gl-comp.m4 seems to have the same issue.

Also, the licence for the generated lib/Makefile.in and lib/Makefile
in Emacs seem confusing/contradictory, perhaps it is related?
Makefile.in starts:

    # Makefile.in generated by automake 1.11.1 from Makefile.am.
    # @configure_input@

    # Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
    # 2003, 2004, 2005, 2006, 2007, 2008, 2009  Free Software Foundation,
    # Inc.
    # This Makefile.in is free software; the Free Software Foundation
    # gives unlimited permission to copy and/or distribute it,
    # with or without modifications, as long as this notice is preserved.

    # This program is distributed in the hope that it will be useful,
    # but WITHOUT ANY WARRANTY, to the extent permitted by law; without
    # even the implied warranty of MERCHANTABILITY or FITNESS FOR A
    # PARTICULAR PURPOSE.

    @SET_MAKE@

    # Copyright (C) 2002-2011 Free Software Foundation, Inc.
    #
    # This file is free software, distributed under the terms of the GNU
    # General Public License.  As a special exception to the GNU General
    # Public License, this file may be distributed as part of a program
    # that contains a configuration script generated by Autoconf, under
    # the same distribution terms as the rest of that program.