debian: Add chips/avr/strtod.c copyright information

This file uses essentially the same license as the files
borrowed from newlib, but has slightly different wording.

Signed-off-by: Keith Packard <keithp@keithp.com>

debian/copyright

@@ -33,6 +33,12 @@ Files:	ports/mega/math_config.h
 Copyright: 2017-2018 Arm Ltd.  All rights reserved.
 License: BSD-3-Clause
 
+Files: chips/avr/strtod.c
+Copyright: Copyright (c) 2002-2005  Michael Stumpf  <mistumpf@de.pepperl-fuchs.com>
+	Copyright (c) 2006,2008  Dmitry Xmelkov
+	All rights reserved.
+License: BSD-3-Clause-avr-libc	
+
 License: GPL-3+
  This package is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
@@ -97,3 +103,29 @@ License: BSD-3-Clause
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
+
+License: BSD-3-Clause-avr-libc
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+ .
+ * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in
+   the documentation and/or other materials provided with the
+   distribution.
+ * Neither the name of the copyright holders nor the names of
+   contributors may be used to endorse or promote products derived
+   from this software without specific prior written permission.
+ .
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ POSSIBILITY OF SUCH DAMAGE.