autoconf: add license

core/autoconf/licenses

@@ -0,0 +1,45 @@
+GPL-2.0-or-later
+GPL-3.0-or-later
+                   AUTOCONF CONFIGURE SCRIPT EXCEPTION
+                       Version 3.0, 18 August 2009
+
+ Copyright (C) 2009 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+This Exception is an additional permission under section 7 of the GNU
+General Public License, version 3 ("GPLv3").  It applies to a given
+file that bears a notice placed by the copyright holder of the file
+stating that the file is governed by GPLv3 along with this Exception.
+
+The purpose of this Exception is to allow distribution of Autoconf's
+typical output under terms of the recipient's choice (including
+proprietary).
+
+0. Definitions
+
+"Covered Code" is the source or object code of a version of Autoconf
+that is a covered work under this License.
+
+"Normally Copied Code" for a version of Autoconf means all parts of
+its Covered Code which that version can copy from its code (i.e., not
+from its input file) into its minimally verbose, non-debugging and
+non-tracing output.
+
+"Ineligible Code" is Covered Code that is not Normally Copied Code.
+
+1. Grant of Additional Permission.
+
+You have permission to propagate output of Autoconf, even if such
+propagation would otherwise violate the terms of GPLv3.  However, if
+by modifying Autoconf you cause any Ineligible Code of the version you
+received to become Normally Copied Code of your modified version, then
+you void this Exception for the resulting covered work.  If you convey
+that resulting covered work, you must remove this Exception in accordance
+with the second paragraph of Section 7 of GPLv3.
+
+2. No Weakening of Autoconf Copyleft.
+
+The availability of this Exception does not imply any general presumption
+that third-party software is unaffected by the copyleft requirements of
+the license of Autoconf.