configure.ac: Change copyright header to refer to version 3 of the GNU General Public License...

	* configure.ac: Change copyright header to refer to version
	3 of the GNU General Public License and to point readers at the
	COPYING3 file and the FSF's license web page.
	* Makefile.def: Likewise.
	* Makefile.tpl: Likewise.
	* Makefile.in: Regenerate.

From-SVN: r146023