graphics/waffle: Update to 1.8.1 and enable testing
Update to 1.8.1:
- Remove obsoleted ${PATCHFILES} for Wayland xdg-shell support
- Port lint housekeeping on ${USES}
https://waffle.freedesktop.org/files/release-notes/waffle-1.8.1.md
PR: 294884
Co-authored-by: Gleb Popov <arrowd@FreeBSD.org>