RFR: 8328812: Update and move siphash license

[Jesper Wilhelmsson]

On Mon, 25 Mar 2024 20:40:50 GMT, Bernd <duke at openjdk.org> wrote:

>> That header only contains a single function declaration for an entry point into the implementation.
>> HotSpot doesn't use that function, and doesn't have anything with a corresponding signature.  So it's
>> not in any way derived from that header.  The HotSpot code is derived from the .c file only, so that's
>> the license we should be referencing.
>
> The problem is that the project is a joined work and has multiple variants of copyrights (see the readme). I don’t think it’s on the safe side to pick a single (non recent) copyright - especially if you change attribution after the fact. But that’s just me. This is especially a problem because the file does NOT contain a dual license claim - the claim is in the readme with this text:
> 
>> Intellectual property
> 
>> This code is copyright (c) 2014-2023 Jean-Philippe Aumasson, Daniel J. Bernstein. It is dual-licensed [CC0](https://github.com/veorq/SipHash/blob/master/LICENCE_CC0) and [MIT](https://github.com/veorq/SipHash/blob/master/LICENSE_MIT).

Copyright and license are two different things. The project has a dual license which we attribute. Code in different files can have different copyrights (as is the case in e.g. our own OpenJDK code). We copied the copyright from the file that we looked at. If you feel it has the wrong copyright please contact the authors of that file and ask them to update their code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18455#discussion_r1538303713