chacha20_poly1305: Use the correct license disclaimer.

[emaste]

Perhaps interesting digression, it turns out the SPDX copy of the 2 clause BSD license has

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

In the tree it looks like AUTHOR is most popular. There are more COPYRIGHT HOLDER than REGENTS:

$ git grep 'THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND'  | wc -l
   10204
$ git grep 'THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER'  | wc -l
    4185
$ git grep 'THIS SOFTWARE IS PROVIDED BY THE REGENTS AND'  | wc -l
    3436

Top-level COPYRIGHT uses AUTHOR.

[imp]

In D33976#768209, @emaste wrote:

Perhaps interesting digression, it turns out the SPDX copy of the 2 clause BSD license has

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

In the tree it looks like AUTHOR is most popular. There are more COPYRIGHT HOLDER than REGENTS:

$ git grep 'THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND'  | wc -l
   10204
$ git grep 'THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER'  | wc -l
    4185
$ git grep 'THIS SOFTWARE IS PROVIDED BY THE REGENTS AND'  | wc -l
    3436

Top-level COPYRIGHT uses AUTHOR.

We recommend AUTHOR and have for 25 or 30 years. Sadly, the folks
that did the upstreaming to the OSI used COPYRIGHT HOLDER for
reasons that are unclear, but that's where *THAT* comes from. Legally
speaking, they are the same thing and the difference between them
would be hard, if not impossible, to litigate.

REGENTS is obsolete and shouldn't be used in new code since
the regents are out of the picture entirely at this point, except
for initial grantor of 4.4BSD, et al.

And it just doesn't matter, at all, in the end. the different granters
are all listed as alliterative texts in the SPDX stuff. The obligations
are still the same to the end user, regardless of which words are used.