Refine LICENSE and README about code parts covered by MIT and GPL-2.0

* LICENSE: Mention MIT and GPL-2.0 at the top of the file; copy
copyrights from README.md; group all copyrights in one block;
explicitly specify which code is covered by MIT and which one by GPL;
remove a statement about the possibility of license change in future.
* README.md: Refine the statement about new code to use C11 atomics;
specify license type at the top of the file.
* README.md (Overview): Mention that README_malloc.txt and
README_stack.txt describe the functionality of libatomic_ops_gpl.
* README.md (Installation and Usage): Mention that libatomic_ops.a is
a core library and libatomic_ops_gpl.a is a gpl extension library;
mention that libatomic_ops_gpl.a licensing details are given in
COPYING and LICENSE files.
* README.md (Copyright & Warranty): Rename to
"Copyright & Warranty, Contributors"; remove all copyrights (they are
moved to LICENSE); better explain the dual nature of the license.

1 files changed, 26 insertions, 15 deletions

diff --git a/LICENSE b/LICENSE
index 95c9db7..2902206 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,12 +1,28 @@
-Our intent is to make it easy to use libatomic_ops, in
-both free and proprietary software.  Hence most code that we expect to be
-linked into a client application is covered by an MIT-style license.
+MIT License (core library) / GPL-2.0 (gpl extension library)
 
-A few library routines are covered by the GNU General Public License.
-These are put into a separate library, libatomic_ops_gpl.a file.
+Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
+Copyright (c) 1999-2011 Hewlett-Packard Development Company, L.P.
+Copyright (c) 2005, 2007 Thiemo Seufer
+Copyright (c) 2007 by NEC LE-IT.  All rights reserved.
+Copyright (c) 2008-2021 Ivan Maidanski
+Copyright (c) 2009 Bradley Smith
+Copyright (c) 2009 by Takashi Yoshii.  All rights reserved.
 
-The low-level part of the library is mostly covered by the following
-license:
+
+Our intent is to make it easy to use libatomic_ops, in both free and
+proprietary software.  Hence most of code (core library) that we expect to
+be linked into a client application is covered by a MIT or MIT-style license.
+
+However, a few library routines (the gpl extension library) are covered by
+the GNU General Public License.  These are put into a separate library,
+libatomic_ops_gpl.a file.
+
+Most of the test code is covered by the GNU General Public License too.
+
+
+The low-level (core) part of the library (libatomic_ops.a) is mostly covered
+by the following license:
 
 ----------------------------------------
 
@@ -33,9 +49,9 @@ SOFTWARE.
 --------------------------------
 
 
-A few files in the atomic_ops/sysdeps directory were inherited in part from
-the Boehm-Demers-Weiser conservative garbage collector, and are covered by
-its license, which is similar in spirit:
+Some files in the atomic_ops/sysdeps directory (part of core library) were
+inherited in part from the Boehm-Demers-Weiser conservative garbage collector,
+and are covered by its license, which is similar in spirit to MIT license:
 
 --------------------------------
 
@@ -58,8 +74,3 @@ A few files are covered by the GNU General Public License.  (See file
 portion of the library.  Thus, atomic_ops_gpl should generally not be
 linked into proprietary code.  (This distinction was motivated by patent
 considerations.)
-
-It is possible that the license of the GPL pieces may be changed for
-future versions to make them more consistent with the rest of the package.
-If you submit patches, and have strong preferences about licensing, please
-express them.