Set default flavor. [1] Make default flavor sdl3 since this is now
the preferred SDL version by upstream starting with this release.
Convert tests to cmake:testing. Note: tests only build for the sdl3
flavor as upstream dropped sdl2 support in the utils required to
run the tests.
Add flavor specifier to games/vvvvvv. [1]
https://github.com/FNA-XNA/FAudio/releases/tag/25.03
Reported by: pkg-fallout [1]
Fixes: 264d97ece00e audio/faudio: add SDL3 flavor (default since 25.03) [1]
1c742619cf