devel/mingw32-pthreads: Update version 2.8.0=>2.9.1
- Add LICENSE LGPL20
- Pet portclippy
- Mark DEPRECATED as last release was in 2012 and mingw32 project is defunct
- Set EXPIRATION_DATE 2023-11-20
Changelog: https://sourceware.org/pthreads-win32/announcement.html