Licenses: introduce SPDX Unique Lincense Identifiers

Like many other projects, U-Boot has a tradition of including big
blocks of License headers in all files.  This not only blows up the
source code with mostly redundant information, but also makes it very
difficult to generate License Clearing Reports.  An additional problem
is that even the same lincenses are referred to by a number of
slightly varying text blocks (full, abbreviated, different
indentation, line wrapping and/or white space, with obsolete address
information, ...) which makes automatic processing a nightmare.

To make this easier, such license headers in the source files will be
replaced with a single line reference to Unique Lincense Identifiers
as defined by the Linux Foundation's SPDX project [1].  For example,
in a source file the full "GPL v2.0 or later" header text will be
replaced by a single line:

        SPDX-License-Identifier:        GPL-2.0+

We use the SPDX Unique Lincense Identifiers here; these are available
at [2].

Note: From the legal point of view, this patch is supposed to be only
a change to the textual representation of the license information,
but in no way any change to the actual license terms. With this patch
applied, all files will still be licensed under the same terms they
were before.

Note 2: The apparent difference between the old "COPYING" and the new
"Licenses/gpl-2.0.txt" only results from switching to the upstream
version of the license which is differently formatted; there are not
any actual changes to the content.

Note 3: There are some recurring questions about linense issues, such
as:
    - Is a "All Rights Reserved" clause a problem in GPL code?
    - Are files without any license header a problem?
    - Do we need license headers at all?

The following excerpt from an e-mail by Daniel B. Ravicher should help
with these:

| Message-ID: <4ADF8CAA.5030808@softwarefreedom.org>
| Date: Wed, 21 Oct 2009 18:35:22 -0400
| From: "Daniel B. Ravicher" <ravicher@softwarefreedom.org>
| To: Wolfgang Denk <wd@denx.de>
| Subject: Re: GPL and license cleanup questions
|
| Mr. Denk,
|
| Wolfgang Denk wrote:
| > - There are a number of files which do not include any specific
| > license information at all. Is it correct to assume that these files
| > are automatically covered by the "GPL v2 or later" clause as
| > specified by the COPYING file in the top level directory of the
| > U-Boot source tree?
|
| That is a very fact specific analysis and could be different across the
| various files.  However, if the contributor could reasonably be expected
| to have known that the project was licensed GPLv2 or later at the time
| she made her contribution, then a reasonably implication is that she
| consented to her contributions being distributed under those terms.
|
| > - Do such files need any clean up, for example should we add GPL
| > headers to them, or is this not needed?
|
| If the project as a whole is licensed under clear terms, you need not
| identify those same terms in each file, although there is no harm in
| doing so.
|
| > - There are other files, which include both a GPL license header
| > _plus_ some copyright note with an "All Rights Reserved" clause. It
| > has been my understanding that this is a conflict, and me must ask
| > the copyright holders to remove such "All Rights Reserved" clauses.
| > But then, some people claim that "All Rights Reserved" is a no-op
| > nowadays. License checking tools (like OSLC) seem to indicate this is
| > a problem, but then we see quite a lot of "All rights reserved" in
| > BSD-licensed files in gcc and glibc. So what is the correct way to
| > deal with such files?
|
| It is not a conflict to grant a license and also reserve all rights, as
| implicit in that language is that you are reserving all "other" rights
| not granted in the license.  Thus, a file with "Licensed under GPL, All
| Rights Reserved" would mean that it is licensed under the GPL, but no
| other rights are given to copy, modify or redistribute it.
|
| Warm regards,
| --Dan
|
| Daniel B. Ravicher, Legal Director
| Software Freedom Law Center (SFLC) and Moglen Ravicher LLC
| 1995 Broadway, 17th Fl., New York, NY 10023
| (212) 461-1902 direct  (212) 580-0800 main  (212) 580-0898 fax
| ravicher@softwarefreedom.org   www.softwarefreedom.org

[1] http://spdx.org/
[2] http://spdx.org/licenses/

Signed-off-by: Wolfgang Denk <wd@denx.de>

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