third_party: remove unused compat/unwind.h

This file is not used since 2012, see commit [1].

NO_DOC=build cleanup
NO_TEST=build cleanup
NO_CHANGELOG=build cleanup

[1]: tarantool/luajit@0187924

Author: Gumix

debian/copyright

@@ -187,36 +187,6 @@ Files: third_party/qsort_arg.c
 Copyright: 1992, 1993 The Regents of the University of California.
 License: BSD-3-Clause
 
-Files: third_party/compat/unwind.h
-Copyright: 2001, 2003, 2004, 2006 Free Software Foundation, Inc.
-License: GPL
- This file is part of GCC.
- .
- GCC 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 2, or (at your option)
- any later version.
- .
- GCC 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 GCC; see the file COPYING.  If not, write to the Free
- Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
- 02110-1301, USA.
- .
- As a special exception, if you include this header file into source
- files compiled by GCC, this header file does not by itself cause
- the resulting executable to be covered by the GNU General Public
- License.  This exception does not however invalidate any other
- reasons why the executable file might be covered by the GNU General
- Public License.
- .
- On Debian systems, the complete text of the GNU General
- Public License can be found in '/usr/share/common-licenses/GPL'.
-
 Files: src/lib/small/third_party/valgrind/*
 Copyright: 2000-2015 Julian Seward.
 License: BSD-4-Clause