[PATCH] Add COPYINGv3 with the GPL version 3 text

[Paul Eggert]

On 2025-11-11 03:15, Florian Weimer wrote:
> The license is referenced in various headers, so we should ship it.

Agreed, but the resulting names are a bit confusing, as COPYING is v2 
but its name does not say "v2".

Also, the existing COPYING and COPYING.LIB files have out-of-date 
contents (they contain US mail addresses that are no longer valid).

So I suggest copying Gnulib's COPYINGv2, COPYINGv3 and COPYING.LESSERv2 
files verbatim, with the same names as Gnulib, and removing the old 
COPYING and COPYING.LIB files.