debian: add licenses for lib/*

* debian/copyright: Here.
* THANKS: Add Michael, who reported the problem.

THANKS

@@ -19,6 +19,7 @@ Jean-Michel Ilié
 Joachim Klein
 Kristin Y. Rozier
 Martin Dieguez Lodeiro
+Michael Tautschnig
 Michael Weber
 Nikos Gorogiannis
 Rüdiger Ehlers

debian/copyright

@@ -101,6 +101,30 @@ License: LGPL-2.1
  On Debian systems, the complete text of the GNU Lesser General Public
  License version 2.1 can be found in "/usr/share/common-licenses/LGPL-2.1".
 
+Files: lib/*
+Copyright: 1991-2014 Free Software Foundation, Inc.
+License: GPL-3+
+ 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 3 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, see <http://www.gnu.org/licenses/>.
+ .
+ On Debian systems, the complete text of the GNU General
+ Public License version 3 can be found in "/usr/share/common-licenses/GPL-3".
+
+Files: lib/alloca.c
+Copyright: (unknown) D A Gwyn
+License: public-domain
+ (Mostly) portable public-domain implementation -- D A Gwyn
+
 Files: debian/*
 Copyright: 2015 Laboratoire de Recherche et Développement de l'Epita (LRDE)
 License: GPL-3+