Hello Fabian. I'm not sure if I could get the person who authored the sndio driver to agree to a license upstream wants, as they don't seem to be around anymore looking at the pull request[1] I based my patch on...
Seeing that it's very unlikely Debian will accept this patch, I'm perfectly fine with closing this bug as wontfix. I will just direct interested sndio users to my website[2] for the patch and let them apply it themselves if they wish to. :) [1] - https://github.com/FluidSynth/fluidsynth/pull/470 [2] - http://rw.rs/~job/software/