[newlib-cygwin] sys/sys: further adoption of SPDX licensing ID tags.

[Sebastian Huber <sh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=160f9f0bf26cf9864bf8f26b1816ae4a3fe13c8d

commit 160f9f0bf26cf9864bf8f26b1816ae4a3fe13c8d
Author: pfg <pfg@FreeBSD.org>
Date:   Mon Nov 27 15:01:59 2017 +0000

    sys/sys: further adoption of SPDX licensing ID tags.
    
    Mainly focus on files that use BSD 2-Clause license, however the tool I
    was using misidentified many licenses so this was mostly a manual - error
    prone - task.
    
    The Software Package Data Exchange (SPDX) group provides a specification
    to make it easier for automated tools to detect and summarize well known
    opensource licenses. We are gradually adopting the specification, noting
    that the tags are considered only advisory and do not, in any way,
    superceed or replace the license texts.

Diff:
---
 newlib/libc/include/sys/tree.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/newlib/libc/include/sys/tree.h b/newlib/libc/include/sys/tree.h
index f4167c4..aef934a 100644
--- a/newlib/libc/include/sys/tree.h
+++ b/newlib/libc/include/sys/tree.h
@@ -3,6 +3,8 @@
 /* $FreeBSD$ */
 
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
  *