Add rules for timity license choices

[pombredanne]

See https://web.archive.org/web/19990218162742/http://www.cgs.fi/~tt/discontinued.html

If you'd like to continue hacking on TiMidity, feel free. I'm hereby extending the TiMidity license agreement: you can now select the most convenient license for your needs from (1) the GNU GPL, (2) the GNU LGPL, or (3) the Perl Artistic License.

This is part of https://github.com/libsdl-org/SDL_mixer/tree/release-3.2.4/src/timidity

This is based on a pots to Fedora legal:

• https://lists.fedoraproject.org/archives/list/legal@lists.fedoraproject.org/thread/OW4G5IHVBELDYGOFC66G72CHPJTCEHLG/

Note the original timidity is at https://web.archive.org/web/19980121134243/http://cgs1.cgs.fi/~tt/timidity/
and it has other licenses, all worthy of ensuring proper detection.