audio/openal-soft: Cleanup options
- Drop bogus FLUIDSYNTH option (MIDI support was removed in 1.17.0)
- The sndio backend is missing capture support. This can lead to crashes when there is no usable fallback backend available. As a workaround always enable the OSS backend when the sndio backend is wanted.
- Prioritize sndio over OSS when it's enabled which should make it unnecessary to fiddle with config files when building with both SNDIO and OSS.
- Turn off dynamically loading backend libs via dlopen
- Correct lib depends
- Update pkg-descr
- Take maintainership